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INFLAMMATION AND IMMUNOPHARMACOLOGY
Laboratories of Immunopharmacology (Y.-N.Z., Y.-F.Y., Y.Z., J.N., Y.-F.F., X.-G.Z., W.T., R.Z., P.-L.H., X.-Y.L., J.-P.Z.) and Natural Products Chemistry (W.-M.Z., Q.-F.L., J.T.), Graduate School of the Chinese Academy of Sciences, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
Received for publication
August 3, 2005
Accepted
October 3, 2005.
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Abstract |
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] production from splenocytes in vitro. Purified T cells from OVA-immunized mice with PSE treatment showed its low ability for activation by OVA plus normal antigen presenting cell stimulation again in vitro. Further studies showed PSE dose dependently inhibited anti-CD3-induced primary T cell proliferation, activation for IL-2R
(CD25) expression, and cytokine (IFN- and IL-2) production also at the transcriptional level. PSE was highly specific and significantly inhibited the activation of extracellular signal-regulated kinase and Jun N-terminal kinase, whereas activation of p38 was not affected in T cells stimulated with anti-CD3. These results demonstrated that PSE is an immunosuppressive compound in P. sepium Bge, which directly inhibits T cell activation in vitro and in vivo. This study provided evidence to understand the therapeutic effects of P. sepium Bge and indicated that this herb is appropriate for treatment of T cell-mediated disorders, such as autoimmune diseases.
). In this study, large numbers of components from P. sepium Bge have been tested in vitro using bioactivity-guided isolation screening assay to identify the most potent immunosuppressive compound that may be responsible for the anti-rheumatoid arthritis effects in P. sepium Bge.
Based on ConA-induced splenocytes proliferation assay, we discovered one compound that has the potent immunosuppressive activity than any others isolated from P. sepium Bge (Supplemental Tables 1 and 2). Using two-dimensional NMR, this compound was identified as a pregnane glycoside named periplocoside E (PSE), which has been reported to be isolated from the anti-tumor fraction of P. sepium (Itokawa et al., 1987, 1988).
To confirm that PSE is the major active component that contributed to the immunosuppressive effect of P. sepium,we investigated the effects of PSE on immune responses. Because activated T lymphocytes play a key role in the onset and pathogenesis of several autoimmune diseases (Perkins, 1998; Xiao and Link, 1999), we tested the inhibitory activities of PSE in T lymphocytes activation in vitro and in vivo and elucidated its immunosuppressive mechanism. We observed its effect on T cell-mediated DNFB-induced delayed-type hypersensitivity (DTH) reaction and ovalbumin (OVA)-induced immune response in vivo. Antigen-presenting assay confirmed that PSE has a direct inhibitory effect on T cell activation in vivo. Further studies then were carried out to examine the effect of PSE on in vitro T cell activation induced by CD3 cross-linking. Moreover, we demonstrated that PSE inhibited T cell activation possibly via its inhibition on the activation of ERK and JNK.
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Materials and Methods |
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Reagents. RPMI 1640 medium was purchased from Invitrogen (Carlsbad, CA). Fetal bovine serum was purchased from Hyclone Laboratories (Logan, UT). [3H]Thymidine (1 mCi/ml) was purchased from Shanghai Institute of Atomic Energy (Shanghai, China). Tetramethylbenzidine and OVA (grade V) were purchased from Sigma-Aldrich (St. Louis, MO). Complete Freund's adjuvant was purchased from Difco (Detroit, MI). Mouse r-IFN-, anti-CD3 (145-2C11), fluorescein isothiocyanate-anti-mouse CD25 (7D4), and all cytokine ELISA kits were obtained from BD Biosciences PharMingen (San Diego, CA).
Animals. Female BALB/c and C57BL/6 mice (6-8 weeks old) were purchased from the Shanghai Experimental Animal Center of the Chinese Academy of Sciences. The animals were housed in specific pathogen-free conditions. All mice were allowed to acclimatize in our facility for 1 week before any experiments were started. All experiments were carried out according to the National Institutes of Health Guide for Care and Use of Laboratory Animals and were approved by the Bioethics Committee of the Shanghai Institute of Materia Medica.
Cell Cultures. Spleens or draining lymph nodes (axillary and inguinal) were removed from mice, and cell suspensions were prepared as described previously with modification (Wu et al., 2005). Erythrocytes in the cells were lysed with Tris-NH4Cl. Cells were cultured with RPMI 1640 supplemented with 10% heat-inactivated fetal bovine serum, 1 mM glutamine, 100 U/ml penicillin, 100 µg/ml streptomycin, and 0.5 µM 2-mercaptoethanol in 96-well flat-bottom plates (Corning 3599; Corning Incorporated, Corning, NY).
MTT Assay. Cytotoxicity was assessed by the MTT assay as previously described (Wu et al., 2005). In brief, splenocytes were cultured in triplicate for 48 h with PSE. The cells cultured with media alone were used as controls. MTT (5 mg/ml) reagent was added 4 h before the end of culture, and then cells were lysed with 10% SDS and 50% N,N-dimethyl formamide, pH 7.2. O.D. values were read at 570 nm, and the percentage of cell viability was calculated.
ConA-Induced Proliferation Assay. Splenocytes (4 x 105 cells/well) were stimulated by ConA (1 µg/ml) in a 96-well plate in triplicate for a 48-h culture. Cells were pulsed with 0.5 µCi/well [3H]thymidine for 8 h and harvested onto glass fiber filters. The incorporated radioactivity was then counted using a Beta Scintillation Counter (MicroBeta Trilux; PerkinElmer Life and Analytical Sciences, Boston, MA).
Mixed Lymphocyte Culture Reaction. BALB/c splenocytes (3 x 105 cells/well) were -irradiated by 30 Gy (Gammacell 3000, Ottawa, ON, Canada) and then cocultured with C57BL/6 splenocytes (3 x 105 cells/well) for 96 h in the presence of PSE. Cells were pulsed with 1 µCi/well [3H]thymidine for 18 h before harvest and assessed for [3H]thymidine incorporation.
DNFB-Induced DTH Reaction. Eight BALB/c mice were prepared for each group. Mice were initially sensitized with 0.5% DNFB dissolved in acetone-olive oil (4:1) on each hind foot on days 0 and 1. On day 9, mice were challenged with 0.4% DNFB on both sides of their left ear (Wu et al., 2005). Vehicle and PSE (1, 5, 25 mg/kg) were administered to each group by i.p. injection 1 h before and 24 h after challenge. Ear swelling was expressed as the difference between the weight of the left and right ear patches obtained from 8-mm punches 40 h after challenge. The punches were obtained in a blinded manner.
OVA-Immunized Mice with Drug Treatment. OVA at 2 mg/ml in phosphate-buffered saline (PBS) was emulsified in an equal volume of complete Freund's adjuvant. The emulsion (100 µl), containing 100 µg of OVA, was injected s.c. into the shaved backs of the BALB/c mice. OVA-immunized mice were administered by i.p. injection with various doses of PSE (2.5, 5, and 10 mg/kg), once daily for 7 days.
Preparation of Purified T Cells and Enriched APC. Primary T cells were purified by using immunomagnetic negative selection to delete B cells and I-A+ APC as described previously (Yang et al., 2002). Lymph node cells were allowed to react with anti-I-Ad/b mAb and then incubated with magnetic particles bound to goat anti-mouse Ig (Polysciences, Inc., Eppelheim, Germany). A T cell population depleted of anti-I-Ad/b-labeled and surface Ig+ cells was obtained by removing cell-bound magnetic particles with a rare earth magnet (Polysciences, Inc.). Purity of the resulting T cell populations was examined by flow cytometry and found to be consistently >95%.
Splenic antigen-presenting cell (APC)-enriched populations were separated using immunomagnetic negative selection to delete the surface Ig+ cells (B cells) and T cells as described previously (Yang et al., 2002). Spleen cells were allowed to react with a mixture of rat anti-mouse CD4 (GK1.5) and rat anti-mouse CD8 (2.43) mAb and then incubated with a mixture of magnetic particles bound to goat anti-rat (Advanced Magnetics, Cambridge, MA) and goat anti-mouse Ig. An APC-enriched population was obtained by removing cell-bound magnetic particles. Purity of the resulting APC-enriched populations was examined by flow cytometry and found to consistently remain as T and B cells less than 1%.
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), alternatively, purified T cells (4 x 105/well) were obtained from OVA-immunized mice with or without PSE treatment; APC-enriched cells (1 x 105/well) were obtained from normal mice and cocultured in 96-well flat-bottomed tissue culture plates in the presence of 100 µg/ml of OVA. Supernatants were harvested at indicated times to measure IFN- and IL-2 levels by ELISA (BD Biosciences PharMingen). For proliferation, cells were pulsed with 1 µCi/well [3H]thymidine for 18 h before harvest and assessed for [3H]thymidine incorporation.
Primary T Cells Stimulated by CD3 Cross-Linking. Purified primary T cells (2 x 105/well) were cultured in 96-well flat-bottom plates that coated with anti-CD3 mAb (5 µg/ml). Culture supernatants were harvested at indicated times to measure IFN- and IL-2 level by ELISA. For proliferation, cells were pulsed with 1 µCi/well [3H]thymidine for 12 h before harvest and assessed for [3H]thymidine incorporation.
For CD25 expression determination, T cells were stimulated in anti-CD3 mAb-coated plates for 12 h, and then cells were harvested for surface staining analysis of CD25 by flow cytometry as described (Yang et al., 2002). In brief, cells were suspended at 5 x 106 cells/ml and stained with fluorescein isothiocyanate-anti-CD25 (7D4) (BD Biosciences PharMingen) for 30 min at 4°C in PBS with 1% FCS. Cells were then washed twice in PBS. The percentage of cells expressing CD25 was determined by flow cytometry.
Reverse Transcription-Polymerase Chain Reaction. Cells lysed with TRIzol (Invitrogen) according to the manufacturer's protocol and total RNA were extracted and reverse-transcribed into cDNA as described previously (Yang et al., 2002). cDNA were amplified for 34 cycles, each composed of 94°C for 30 s, 55°C for 30 s, and 70°C for 60 s. At the end of 34 cycles, samples were separated by a 1.2% agarose gel and stained with ethidium bromide.
Primer sequences were as follows: IL-2, sense primer, 5'-CTTCAAGCTCCACTTCAAGC-3', and antisense primer, 5'-GCTTTGAGAAAGGGCTATCCA-3'; IFN-, sense primer, 5'-AACGCTTA CACACTGCATCTTGG-3', and antisense primer, 5'-GACTTCAAAGAGTCTGAGG-3'; and hypoxanthine guanine phosphoribosyl transferase sense primer, 5'-GTTGGATACAGGCCAGACTTTGTTG-3', and antisense primer 5'-GAGGGTAGGCTGGCCTATAGGCT-3'
Western Blotting. Whole-cell extracts were obtained from T cells as previously described (Tsitoura and Rothman, 2004). One hundred micrograms of total cell protein was resolved by SDS-polyacrylamide gel electrophoresis on 10% polyacrylamide gels and electroblotted onto polyvinylidene diflouride membranes (GE Healthcare, Little Chalfont, Buckinghamshire, UK). After saturation of nonspecific binding sites with 5% bovine serum albumin in Tris-buffered saline-Tween 20, the membranes were probed overnight with the appropriate antibody against phosphorylated ERK, ERK, phosphorylated JNK, JNK, phosphorylated p38, and p38 (Cell Signaling Technology Inc., Beverly, MA) and subsequently incubated with a secondary HRP-labeled anti-IgG antibody. Finally, the membranes were treated with chemiluminescent detection reagents (GE Healthcare) and processed for autoradiography.
Statistical Analysis. Student's t test was used to determine significance between groups where appropriate. p < 0.05 was considered significant.
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Results |
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(Kobayashi et al., 2001). Figure 3 illustrated the inhibitory effect of PSE on DNFB-induced DTH reaction. When administered at dosages of 5 or 25 mg/kg PSE, ear swelling was suppressed by 53.9 and 64.6%, respectively. PSE exposure did not produce any signs of overt toxicity or any significant changes in relative organ weights. The results suggest that in vivo exposure to PSE had a suppressive effect on T cell-dependent immune responses.
PSE Suppressed OVA-Induced Antigen-Specific Immune Responses. To confirm the effect of in vivo treatment with PSE on T cell-mediated immune response, OVA, a T cell-dependent Ag, induced immune response was examined as follows. BALB/c mice were once daily administrated by an i.p. injection with 2.5, 5, or 10 mg/kg of PSE for 7 days after immunization with OVA, and the splenocytes were harvested to measure the proliferative responses to OVA in vitro. As shown in Fig. 4A, when cultured with OVA for 72 h, the proliferation of splenocytes from mice treated with PSE at 2.5, 5, and 10 mg/kg were significantly inhibited compared with vehicle mice. Furthermore, we analyzed the cytokines produced by splenocytes in response to OVA. As shown in Fig. 4, B and C, IL-2 and IFN- produced by splenocytes from mice treated with PSE were also severely depressed. However, administration of PSE more significantly reduced OVA-induced IFN- production than IL-2. As shown in Fig. 4, B and C, the lowest dose (2.5 mg/kg) of PSE still showed potent inhibition of IFN- production, whereas it showed no inhibition on IL-2 production by splenocytes.
PSE Directly Inhibited Anti-OVA T Cell Responses. It then became important to examine whether administration of PSE directly influences the anti-OVA T cell responses. The capacity of T cells to respond to OVA was determined in the antigen-presenting assay. Purified T cells prepared from different groups of mice were stimulated with OVA in the presence of an enriched APC prepared from normal mice. The results of Fig. 5A demonstrated that in the presence of normal APC, T cells from immunized mice showed the high proliferative responses with OVA stimulation. PSE treatment significantly inhibited the proliferative responses of T cells. We also examined the capacity of T cells from immunized mice to produce IL-2 and IFN- in response to OVA stimulation. Like proliferation, T cells from mice treated with PSE produced significantly lower amounts of IL-2 and IFN- upon OVA stimulation (Fig. 5, B and C). The decreased expression of IL-2 and IFN- mRNA paralleled that of protein secretion (Fig. 5D). These results indicated that administration of PSE had a direct suppression on anti-OVA T cell responses, and the main targets for the immunosuppressive PSE have been considered to be T cells.
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). Primary T cells were pretreated with or without PSE for 30 min and were tested for anti-CD3-induced proliferative responses. As shown in Fig. 6A, PSE (0.063
4 µM) concentration dependently inhibited T cell proliferation induced by anti-CD3 stimulation.
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Anti-CD3 cross-linking induced IL-2R -chain (CD25) assembles with 
and subunits to form the high-affinity IL-2R. IL-2 regulates proliferation of T cells in concert with induced expression of high-affinity cytokine receptors. The absence of CD25 expression would certainly impair the responsiveness of T cells to the cytokine IL-2, an event that is required for proliferative response (Zella et al., 2000). Flow cytometry analysis revealed a marked delay in the appearance of CD25+ cells in the PSE (0.0164 µM)-treated cells, as opposed to the untreated control (Fig. 6B). This delay was observed as early as 8 h after anti-CD3 stimulation and persisted until 18 h after stimulation (data not shown).
IL-2 and IFN- are produced and released upon T cell activation. PSE (0.0164 µM) exerted a profound, concentration-dependent inhibitory effect on IFN- production from anti-CD3 activated T cells (Fig. 6D). PSE (14 µM) also significantly inhibited the production of IL-2 (Fig. 6C). However, decrease in the production of IFN- was more significant than that of IL-2. To define at which stage of the induction process PSE alters the production of cytokines, we next examined its effect on cytokine mRNA expression. Primary T cells were activated with anti-CD3 mAb in the presence or absence of PSE. After 8 and 18 h of culture, total RNA was extracted, and the cytokine mRNA expressions were detected by reverse transcription-polymerase chain reaction. Marked induction of IL-2 and IFN- mRNA occurred by 8 h, and expression was further induced at 18 h. As shown in Fig. 6E, PSE strongly suppressed IFN- and IL-2 mRNA induction in a dose-dependent manner. Therefore, for these particular cytokines, the modulation of mRNA expression parallels that of protein secretion as detected in culture supernatants, suggesting that PSE affects predominantly gene transcription and/or transcript stability.
PSE Reduced Phosphorylation of ERK and JNK in Anti-CD3 Activated T Cells. From the above studies, it is evident that PSE was a strong inhibitor of T cell responses both in vitro and in vivo. We next examined the possible mechanism by which the PSE may have mediated its inhibitory activity. Each of the mitogen-activated protein kinases, ERK1/2, JNK, and p38, has been demonstrated to play central roles in T cell proliferation and cytokine production (Matsuda et al., 1998; Werlen et al., 1998; Ghaffari-Tabrizi et al., 1999; Li et al., 1999). Thus, the effects of the PSE on the activation of ERK1/2, JNK, and p38 were examined. Prior to T cell stimulation, phosphorylation of ERK1/2, JNK, or p38 was not observed in either the control or the PSE-treated group. In contrast, stimulation with anti-CD3 was associated with ERK1/2, JNK, and p38 phosphorylation (Fig. 7). The phosphorylation of ERK1/2, JNK, and p38 was assessed at 10 min, 2 h, and 30 min, respectively, after cross-linking with anti-CD3. These time points were chosen because they correspond to the peak activity of these kinases in response to TCR triggering. Pretreatment of T cells with PSE (1 and 4 µM) was found to greatly decrease ERK1/2 and JNK activation but not the activation of p38 (Fig. 7).
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, 1988), there was no information available for its immune activity. In this study, we discovered the potent immunosuppressive activity of PSE in vitro and in vivo. PSE may be responsible for the anti-autoimmune diseases properties of P. sepium.
Our studies have demonstrated that PSE was a potent inhibitor of T cell activation. In vitro, PSE significantly inhibited T cell proliferation, cytokine production, and CD25 expression. In vivo treatment of PSE suppressed T cell-mediated DNFB-induced DTH reaction. Response of T cells to OVA, a T cell-dependent Ag, was similarly inhibited. Moreover, PSE selectively suppressed ERK and JNK activation, but not p38 induced by TCR stimulation.
T cell-mediated autoimmune diseases or inflammatory diseases are associated with T cell overactivation or unbalanced Th1-/Th2-type immune responses (Schulze-Koops and Kalden, 2001; Van Eden et al., 2002; Kidd, 2003). PSE concentration-dependently inhibited T cell proliferation induced by TCR cross-linking stimulation, mitogen (ConA), allogen, or T cell-dependent antigen (OVA). That suggested PSE could be able to restrict the overactive or self-reactive T cell from overexpansion. PSE also markedly prevent Th1-type cytokine (IL-2 and IFN-) production, especially for IFN- production. The results indicated that PSE could suppress Th1-type inflammatory diseases by suppressing Th1-type responses. DNFB-induced DTH reaction is a CD4+ T cell-mediated pathologic response involved with T cell activation and the production of Th1-type cytokines, such as IL-2, which is a propagator of T cell activation, and IFN-, which is involved in the effect phase of the DTH response (Kobayashi et al., 2001). PSE may modify DTH reaction through restraining T cell activation or IL-2 and IFN- production. Whether PSE has an effect on other Th-1-type response-mediated autoimmune diseases or inflammatory diseases warrants further investigation.
The mechanisms by which the PSE inhibited T lymphocyte activation were partly identified. The action of this compound was highly specific, with the activation of ERK and JNK significantly inhibited, whereas activation of p38 was not affected. Although PSE did not inhibit the phosphorylation of p38, it may inhibit the activity of p-p38. The activity of p-p38 was analyzed in an in vitro kinase assay. Results shown in Supplemental Fig. 1 suggested PSE do not inhibit the activity of p-p38. In T cells, upon triggering of the TCR, activation of the MEK/ERK pathway routes signals that are critical for cellular activation, proliferation, and production of cytokines important for the regulation of immune responses (Whitehurst et al., 1992; Karin, 1995; DeSilva et al., 1996; Fields et al., 1996; Li et al., 1996; Alberarola-Ila et al., 1997; Baumgarth et al., 1997). Activation of ERK has been demonstrated to be critical for the proliferation and production of IL-2 in murine primary T cells (Koike et al., 2003). The importance of the JNK cascade in T cell activation and production of IFN- has also been demonstrated (Liu et al., 1997; Yang et al., 1998; Sabapathy et al., 1999; Dong et al., 2000; Behrens et al., 2001). Because PSE (
1 µM) could inhibit the phosphorylation of ERK1/2 and JNK in anti-CD3 activated T cells, the effects of PSE were compared with the inhibitors of ERK1/2 and JNK signal pathway in anti-CD3-induced T cell proliferation and IL-2 and IFN- production assays. The results shown in Supplemental Fig. 2 suggested PSE (1 µM) had similar inhibitory effects as PD98059 and SP600125 on anti-CD3-induced T cell proliferation and IL-2 and IFN- production. However, the inhibition of ERK and JNK activities by PSE is not completely consistent with its ability to suppress lymphocyte function. PSE with lower concentrations (<1 µM) still showed distinguished inhibition on T cell proliferation and IFN- production but no effect on ERK and JNK activation. It indicated that there are other mechanisms involved in it.
Another possible mechanism for PSE inhibiting T cell proliferation is that PSE could inhibit IL-2R expression and, consequently, inhibited IL-2-induced signaling pathway. The immune response is initiated by TCR ligation, which causes resting T cells to exit G0 and enter G1 of the cell cycle. IL-2 and IL-2R expression, which drive T cell progression past the G1 checkpoint, thus enable proliferation to occur (Nelson and Willerford, 1998). Since the inhibition of CD3-activated T cell proliferation by PSE could not be overcome by adding exogenous IL-2 to stimulate IL-2 receptor pathway (data not shown), it suggested the proliferations could be blocked by PSE interfering with IL-2R binding/signaling. As flow cytometry analysis data have shown, the appearance of CD25+ T cells was delayed by PSE (0.0164 µM) treatment during first 8- to 18-h culture, when primary T cells were stimulated with anti-CD3. These results support the conclusion that modulation of cell surface receptors may be a mechanism involved in the inhibition of lymphocyte proliferation by PSE.
This study elucidated these involved mechanisms could be combined and responsible for the inhibitory effects of PSE in vitro and in vivo. We demonstrated that PSE is as a potent inhibitor for inhibiting the early events of T cell receptor-mediated T cell activation by blocking the ERK and JNK pathway and the late events of T cell activation by delaying IL-2R (CD25) expression.
In conclusion, the results from this study establish that PSE, an active natural product compound identified in P. sepium Bge, exhibits low cytotoxicity and compelling immunosuppressive effects, which directly suppress T cell activation in vitro and in vivo. Through the study of PSE, we get a further understanding on the therapeutic effects of the traditional Chinese herb medicine, P. sepium Bge, in treatment of autoimmune diseases such as rheumatoid arthritis. This study also provides an immunosuppressive natural product compound for us to further studies in chemistry and pharmacology.
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Footnotes |
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ABBREVIATIONS: ConA, concanavalin A; PSE, periplocoside E; DNFB, 2,4-dinitrofluorobenzene; DTH, delayed-type hypersensitivity; OVA, ovalbumin; ERK, extracellular signal-regulated kinase; JNK, Jun N-terminal kinase; IFN, interferon; ELISA, enzyme-linked immunosorbent assay; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; PBS, phosphate-buffered saline; APC, antigen-presenting cell; IL, interleukin; TCR, T cell antigen receptor; mAb, monoclonal antibody.
The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material. 
1 Both authors contributed equally to this work.
Address correspondence to: Dr. Jian-Ping Zuo, Laboratory of Immunopharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Zhangjiang Hi-Tech Park, Shanghai 201203, People's Republic of China. E-mail: jpzuo{at}mail.shcnc.ac.cn
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References |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Alberarola-Ila J, Takaki S, Kerner JD, and Perlmutter RM (1997) Differential signaling by lymphocyte antigen receptors. Annu Rev Immunol 15: 125-154.[CrossRef][Medline]
Baumgarth N, Egerton M, and Kelso A (1997) Activated T cells from draining lymph nodes and an effector site differ in their responses to TCR stimulation. J Immunol 159: 1182-1191.[Abstract]
Behrens A, Sabapathy K, Graef I, Cleary M, Crabtree GR, and Wagner EF (2001) Jun N-terminal kinase 2 modulates thymocyte apoptosis and T cell activation through c-Jun and nuclear factor of activated T cell (NF-AT). Proc Natl Acad Sci USA 98: 1769-1774.
DeSilva DR, Feeser WS, Tancula EJ, and Scherle PA (1996) Anergic T cells are defective in both jun NH2-terminal kinase and mitogen-activated protein kinase signaling pathways. J Exp Med 183: 2017-2023.
Dong C, Yang D, Tournier C, Whitmarsh A, Xu J, Davis R, and Flavell R (2000) JNK is required for effector T-cell function but not for T-cell activation. Nature (Lond) 405: 91-94.[CrossRef][Medline]
Fields PE, Gajewski TF, and Fitch FW (1996) Blocked Ras activation in anergic CD4+ T cells. Science (Wash DC) 271: 1276-1278.[Abstract]
Ghaffari-Tabrizi N, Bauer B, Villunger A, Baier-Bitterlich G, Altman A, Utermann G, Uberall F, and Baier G (1999) Protein kinase C-theta, a selective upstream regulator of JNK/SAPK and IL-2 promoter activation in Jurkat T cells. Eur J Immunol 29: 132-142.[CrossRef][Medline]
Itokawa H, Xu JP, and Takeya K (1987) Studies on chemical constituents of antitumor fraction from Periploca sepium BGE. I. Chem Pharm Bull 35: 4524-4529.[Medline]
Itokawa H, Xu JP, and Takeya K (1988) Studies on chemical constituents of antitumor fraction from Periploca sepium: IV. Structures of new pregnane glycosides, periplocosides D, E, L and M. Chem Pharm Bull 36: 2084-2089.[Medline]
Karin M (1995) The regulation of AP-1 activity by mitogen-activated protein kinases. J Biol Chem 270: 16483-16486.
Kidd P (2003) Th1/Th2 balance: the hypothesis, its limitations and implications for health and disease. Altern Med Rev 8: 223-246.[Medline]
Kobayashi K, Kaneda K, and Kasama T (2001) Immunopathogenesis of delayed-type hypersensitivity. Microsc Res Tech 53: 241-245.[CrossRef][Medline]
Koike T, Yamagishi H, Hatanaka Y, Fukushima A, Chang JW, Xia Y, Fields M, Chandler P, and Iwashima M (2003) A novel ERK-dependent signaling process that regulates interleukin-2 expression in a late phase of T cell activation. J Biol Chem 278: 15685-15692.
Li W, Whaley CD, Mondino A, and Mueller DL (1996) Blocked signal transduction to the ERK and JNK protein kinases in anergic CD4+ T cells. Science (Wash DC) 271: 1272-1276.[Abstract]
Li XY (1991) Immunomodulating Chinese herbal medicines. Mem Inst Oswaldo Cruz 86 (Suppl 2): 159-164.[Medline]
Li YQ, Hii CS, Costabile M, Goh D, Der CJ, and Ferrante A (1999) Regulation of lymphotoxin production by the p21ras-raf-MEK-ERK cascade in PHA/PMA-stimulated Jurkat cells. J Immunol 162: 3316-3320.
Liu B, Carle KW, and Whisler RL (1997) Reductions in the activation of ERK and JNK are associated with decreased IL-2 production in T cells from elderly humans stimulated by the TCR/CD3 complex and costimulatory signals. Cell Immunol 182: 79-88.[CrossRef][Medline]
Matsuda S, Moriguchi T, Koyasu S, and Nishida E (1998) T lymphocyte activation signals for interleukin-2 production involve activation of MKK6-p38 and MKK7-SAPK/JNK signaling pathways sensitive to cyclosporin A. J Biol Chem 273: 12378-12382.
Nelson BH and Willerford DM (1998) Biology of the interleukin-2 receptor. Adv Immunol 70: 1-81.[Medline]
Perkins DL (1998) T-cell activation in autoimmune and inflammatory diseases. Curr Opin Nephrol Hypertens 7: 297-303.[Medline]
Sabapathy K, Hu Y, Kallunki T, Schreiber M, David JP, Jochum W, Wagner EF, and Karin M (1999) JNK2 is required for efficient T-cell activation and apoptosis but not for normal lymphocyte development. Curr Biol 9: 116-125.[CrossRef][Medline]
Schulze-Koops H and Kalden JR (2001) The balance of Th1/Th2 cytokines in rheumatoid arthritis. Best Pract Res Clin Rheumatol 15: 677-691.[CrossRef][Medline]
Tsitoura DC and Rothman PB (2004) Enhancement of MEK/ERK signaling promotes glucocorticoid resistance in CD4+ T cells. J Clin Investig 113: 619-627.[CrossRef][Medline]
Van Eden W, Van Der Zee R, Van Kooten P, Berlo SE, Cobelens PM, Kavelaars A, Heijnen CJ, Prakken B, Roord S, and Albani S (2002) Balancing the immune system: Th1 and Th2. Ann Rheum Dis 61 (Suppl 2): ii25-ii28.
Werlen G, Jacinto E, Xia Y, and Karin M (1998) Calcineurin preferentially synergizes with PKC-theta to activate JNK and IL-2 promoter in T lymphocytes. EMBO (Eur Mol Biol Organ) J 17: 3101-3111.[CrossRef][Medline]
Whitehurst CE, Boulton TG, Cobb MH, and Geppert TD (1992) Extracellular signal-regulated kinases in T cells: anti-CD3 and 4-phorbol 12-myristate 13-acetate-induced phosphorylation and activation. J Immunol 148: 3230-3237.[Abstract]
Wu QL, Fu YF, Zhou WL, Wang JX, Feng YH, Liu J, Xu JY, He PL, Zhou R, Tang W, et al. (2005) Inhibition of S-adenosyl-L-homocysteine hydrolase induces immunosuppression. J Pharmacol Exp Ther 313: 705-711.
Xiao BG and Link H (1999) Antigen-specific T cells in autoimmune diseases with a focus on multiple sclerosis and experimental allergic encephalomyelitis. Cell Mol Life Sci 56: 5-21.[CrossRef][Medline]
Yang DD, Conze D, Whitmarsh AJ, Barrett T, Davis RJ, Rincon M, and Flavell RA (1998) Differentiation of CD4+ T cells to Th1 cells requires MAP kinase JNK2. Immunity 9: 575-585.[CrossRef][Medline]
Yang YF, Mukai T, Gao P, Yamaguchi N, Ono S, Iwaki H, Obika S, Imanishi T, Tsujimura T, Hamaoka T, et al. (2002) A non-peptide CCR5 antagonist inhibits collagen-induced arthritis by modulating T cell migration without affecting anti-collagen T cell responses. Eur J Immunol 32: 2124-2132.[CrossRef][Medline]
Zella D, Romerio F, Curreli S, Secchiero P, Cicala C, Zagury D, and Gallo RC (2000) IFN-alpha 2b reduces IL-2 production and IL-2 receptor function in primary CD4+ T cells. J Immunol 164: 2296-2302.
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  Y.-F. Fu, Y.-N. Zhu, J. Ni, X.-G. Zhong, W. Tang, Y.-D. Re, L.-P. Shi, J. Wan, Y.-F. Yang, C. Yuan, et al. A Reversible S-Adenosyl-L-Homocysteine Hydrolase Inhibitor Ameliorates Experimental Autoimmune Encephalomyelitis by Inhibiting T Cell Activation J. Pharmacol. Exp. Ther., November 1, 2006; 319(2): 799 - 808. [Abstract] [Full Text] [PDF]
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Y.-N. Zhu, X.-G. Zhong, J.-Q. Feng, Y.-F. Yang, Y.-F. Fu, J. Ni, Q.-F. Liu, W. Tang, W.-M. Zhao, and J.-P. Zuo Periplocoside E Inhibits Experimental Allergic Encephalomyelitis by Suppressing Interleukin 12-Dependent CCR5 Expression and Interferon-{gamma}-Dependent CXCR3 Expression in T Lymphocytes J. Pharmacol. Exp. Ther., September 1, 2006; 318(3): 1153 - 1162. [Abstract] [Full Text] [PDF]
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