Apoptosis induced by in vitro infection with simian-human immunodeficiency chimeric virus in macaque and human peripheral blood mononuclear cells

We investigated apoptosis induced by in vitro infection with the chimeric virus of simian immunodeficiency virus and human immunodeficiency virus (SHIV). Macaque and human peripheral blood mononuclear cells (PBMCs) were infected with pathogenic SHIV-89.6p (89.6p) or nonpathogenic SHIV-NM-3rN (NM-3rN). In macaque PBMCs, the extent of virus production and apoptosis induction in CD4(+) cells was much greater in 89.6p infection than in NM-3rN infection. The result was consistent with our previous study of in vivo SHIV infection. In human PBMCs, 89.6p replicated and induced apoptosis more extensively than did NM-3rN, when the cells were infected with the same infectious doses of the viruses. However, in cells infected with a high dose of NM-3rN, the levels of virus production and apoptosis induction were comparable to those in 89.6p infection. There was no significant difference in the extent of apoptosis induction between 89.6p and NM-3rN infection when growth curves of the two viruses matched. Thus, apoptosis induction by SHIV might depend quantitatively on the amount of virus production rather than on the strains of the virus. Moreover, the correlation between the extent of apoptosis induction and virus pathogenicity in macaque PBMCs has also been found in SHIV-infected macaques. This suggests that the profiles of SHIV infection in vitro reflect the in vivo phenomena. Therefore, the in vitro evaluation of apoptosis induction by SHIV could be useful as a safety test for the development of live-attenuated vaccines.

Expression of membrane-type 1 matrix metalloproteinase in rheumatoid synovial cells

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is thought to be a putative regulator of pro-gelatinase A (MMP-2) in the rheumatoid synovium. In this study, we examined the effects of IL-1beta, one of the inflammatory cytokines, on the expression of MT1-MMP and the activation of pro-MMP-2 using rheumatoid synovial cells. We also studied the effects of KE-298 (2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid), a new disease-modifying anti-rheumatic drug (DMARD), on MT1-MMP expression of rheumatoid synovial cells. Type B synovial cells (fibroblast-like synovial cells) were cultured with KE-298 (25-100 microg/ml) in the presence of IL-1beta for 48 h. Activation of pro-MMP-2 secreted from synovial cells was analysed by gelatin zymography. Reverse transcription-polymerase chain reaction (RT-PCR) methods were used to detect MT1-MMP mRNA. MT1-MMP protein expression on synovial cells was examined by anti-MT1-MMP immunoblot. An active form of MMP-2 was demonstrated in the culture media conditioned by IL-1beta-stimulated synovial cells. In addition, MT1-MMP mRNA and protein expression of rheumatoid synovial cells were increased by IL-1beta treatment. KE-298 blocked this IL-1beta-induced pro-MMP-2 activation and MT1-MMP expression, but did not affect IL-1beta-induced tissue inhibitor of metalloproteinase-2 (TIMP-2) secretion from rheumatoid synovial cells. These findings indicate that activation of rheumatoid synovial cells by IL-1beta results in the induction of MT1-MMP expression. Given that MT1-MMP promotes matrix degradation by activating pro-MMP-2, these results suggest a novel mechanism whereby cytokine may contribute to articular destruction in rheumatoid arthritis (RA). KE-298 may prevent this process by down-regulating MT1-MMP expression.

Effect of gravity change on the production of thrombopoietic growth factors

It is reported that the stay in the space develops anemia, thrombocytopenia, and altered function and structure of red blood cell. The mechanism of these abnormalities was not clarified yet. The cloning of the thrombopoietin (TPO), followed by the analysis of TPO and c-mpl (its cellular receptor) knockout mice confirmed its role as the primary regulator of thrombopoiesis. TPO has been shown to stimulate both megakaryocyte colony growth from marrow progenitor cells and the maturation of immature megakaryocyte to form functional platelet. This process includes the massive cytoskeletal rearrangement, such as proplatelet formation and fragmentation of proplatelet. In this study we have focused on the production of thrombopoietic growth factors in mice those were exposed to gravity change by parabolic flight (PF).

Dynamic biosynthesis of heparan sulphate sequences in developing mouse brain: a potential regulatory mechanism during development

Over recent years our understanding of the functions of the heparan sulphate (HS) family of complex polysaccharides has shifted dramatically. Once seen as simply structural scaffolding in the extracellular matrix, they are now viewed as critical players in the regulatory network of cells. They are strategically located at the cell surface and in the extracellular matrix, and there has been an increasing realization that specific sequences in the HS chains are designed for selective interactions with many proteins. Functionally, these interactions result in regulation of the protein activities. It is becoming clear that HS functions as a new class of multifunctional cell regulator. There is also growing evidence that cells can dynamically alter the structure of HS sequences that they express. Here we review recent developments and describe evidence for regulated changes in the synthesis and structure of HS chains expressed during early mouse brain development. The data suggest a new concept in which dynamic changes in biosynthesis of different HS sequences create distinct cellular HS repertoires, the heparanome. Their expression, in specific spatio-temporal patterns, is likely to endow organisms with novel regulatory mechanisms for controlling the activity of specific HS-binding proteins.

Moving-table reduced-dose gadolinium-enhanced three-dimensional magnetic resonance angiography: velocity-dependent method with three-phase gadolinium infusion

The purpose of this study was to develop a method for reducing gadolinium dose and suppressing venous overlap in moving-table three-dimensional (3D) magnetic resonance (MR) angiography from the abdomen to the feet. Thirty-one patients underwent three-phase infusion of 16-18 mL of gadolinium: infusion rates and imaging times were determined after taking into account mean blood flow velocity, so that image acquisition was synchronized with peak arterial enhancement at both the first and third stations (velocity-dependent method). Twenty-three other patients underwent slow infusion of 38 mL of gadolinium with fixed acquisition time (high-dose method). The image quality for the two methods was compared. The velocity-dependent method produced good image quality with significantly less venous overlap than the high-dose method, especially in the below-the-knee region (P <.001). The velocity-dependent method provides satisfactory MR angiograms using 16-18 mL of gadolinium in patients having various blood flow velocities.

Isolation and structure of korolkoside, a bis-iridoid glucoside from Lonicera korolkovii

A new bis-iridoid glucoside, korolkoside (1), was isolated from Lonicera korolkovii, and its structure and stereochemistry were determined by spectroscopic analysis and chemical derivatization. Korolkoside (1) consists of two secologanin moieties that are connected by an acetal linkage.

Nitric oxide protects cultured rheumatoid synovial cells from Fas-induced apoptosis by inhibiting caspase-3

Nitric oxide (NO) is elevated in the synovial fluids and sera of patients with rheumatoid arthritis (RA) and is thought to be an important proinflammatory mediator in the rheumatoid synovium. To test the hypothesis that NO might modulate the apoptosis-inducing signal pathway, we investigated the effects of NO on rheumatoid synovial-cell apoptosis induced by Fas ligation with anti-Fas antibody. Pretreatment of synovial cells with the NO donor S-nitro-N-acetylpenicillamine (SNAP) prevented the Fas-mediated induction of apoptosis. The activation of caspase-3 was required to mediate Fas-induced synovial cell apoptosis. The NO donor SNAP inhibited Fas-induced caspase-3 activation in rheumatoid synovial cells. However, NO did not interrupt Fas-induced caspase-8 cleavage or subsequent cytochrome c release into the cytosol in rheumatoid synovial cells. These data indicate that NO prevents apoptosis in rheumatoid synovial cells by directly inhibiting caspase-3 activation. Thus, we propose that NO interferes with cell death signal transduction and may contribute to rheumatoid synovial cell proliferation by inhibiting induction of apoptosis.

Relation between cytokines and Helicobacter pylori in gastric cancer

BACKGROUND

Helicobacter pylori is etiologically involved in the development of gastric cancer and infected gastric mucosa has been shown to possess elevated levels of cytokines [for example interleukin (IL)-1beta, IL-6 and IL-8]. Because specific cytokines have also been shown to enhance the development of certain cancers, we examined the relationship between the levels of cytokines, the type and stage of gastric cancers, and the H. pylori infection.

MATERIALS AND METHODS

Cytokines were measured from gastric cancer tissues, adjacent normal appearing mucosa, and the serum in 66 patients with early or advanced gastric cancer and from controls using semiquantitative RT-PCR and ELISA.

RESULTS

IL-6 and IL-8 levels were more than 10-fold increased in cancer tissues as compared with normal gastric tissues. IL-8 levels in cancer tissues were more than 2-fold higher in advanced gastric cancer as compared with early gastric cancer irrespective of H. pylori status. IL-6 levels were significantly higher in early gastric cancer with active H. pylori infection as compared with early cancer without H. pylori infection (8.7 + 1.4 vs. 1.2 + 0.3 pg/mg protein, p <.001) and decreased significantly after the cure of H. pylori (11.1 + 2.9-8.2 + 2.3 pg/mg protein, p <.05).

CONCLUSIONS

IL-8 levels in gastric cancer tissue are largely independent of H. pylori infection. In contrast, tissue IL-6 levels were high in H. pylori infected early gastric cancer and fell significantly after the cure of H. pylori suggesting a relationship between H. pylori infection and early gastric cancer.

Pars plana vitrectomy for cystoid macular edema secondary to sarcoid uveitis

OBJECTIVE

To examine the results of pars plana vitrectomy for cystoid macular edema secondary to sarcoid uveitis resistant to medical treatment.

DESIGN

Retrospective, interventional, noncomparative case series.

SUBJECTS

Fourteen consecutive subjects (18 eyes) with cystoid macular edema associated with sarcoid uveitis resistant to medical treatment.

INTERVENTION

All eyes underwent pars plana vitrectomy. Nine eyes also underwent peeling of the epiretinal membrane or removal of the posterior vitreous cortex.

MAIN OUTCOME MEASURES

Status of macular edema, visual acuity, and complications.

RESULTS

Ten eyes (56%) improved 2 or more lines of Snellen visual acuity within 12 months. Six eyes (33%) remained unchanged, within a line of preoperative Snellen visual acuity, and two eyes (11%) worsened by 2 or more lines of Snellen visual acuity. Slit-lamp biomicroscopy showed that cystoid macular edema had resolved in 14 eyes (78%) within 9 months postoperatively. One eye (6%) had minimal edema, whereas three eyes (17%) remained unchanged biomicroscopically at the final visit. Postoperative complications included cataract formation, glaucoma, optic nerve atrophy, epiretinal membrane formation, and tractional retinal detachment. No severe postoperative inflammation was noted.

CONCLUSIONS

Pars plana vitrectomy seems to have a beneficial effect on cystoid macular edema caused by sarcoidosis resistant to medical treatment.

Difference in thioredoxin expression in viral myocarditis in inbred strains of mice

Redox regulating mechanisms may be involved in the pathogenesis of viral myocarditis and thioredoxin (TRX) is a small multifunctional protein that contains a redox active sequence. The present study investigated the histopathology and characteristics of TRX expression in acute coxsackievirus B3 myocarditis in inbred strains of mice (severe myocarditis in DBA/2 mice, moderate myocarditis in BALB/c mice and mild myocarditis in C57BL/6 mice). Thioredoxin was upregulated and its expression correlated with the severity of the disease. In addition, 8-hydroxy-2'-deoxyguanosine, which is an established marker for oxidative stress, was concominantly positive in damaged myocytes. Thus, TRX may be specifically induced by the acute inflammatory stimuli in murine viral myocarditis, and the severity and development of acute viral myocarditis may be regulated by the cellular redox state.

Cloning and expression of CitPDS1, a gene encoding phytoene desaturase in citrus

A cDNA clone encoding phytoene desaturase (PDS) was isolated from citrus (Citrus unshiu Marc.). The transcript of the isolated PDS (CitPDS1) was not detected by conventional RNA gel-blot analysis; instead, it was detected by a sensitive reverse transcription-PCR (RT-PCR). The CitPDS1 transcript in the juice sacs/segment epidermis (edible part) was at a low level in the young fruit, and it increased toward maturation like citrus phytoene synthase (CitPSY1). In the peel, in contrast to CitPSY1, the transcript of which was induced toward maturation, the level of the CitPDS1 transcript remained constant after an increase in July, indicating non-coordinate regulation of CitPDS1 and CitPSY1 in the peel.

Upregulation of iNOS by COX-2 in muscularis resident macrophage of rat intestine stimulated with LPS

We investigated the effect of lipopolysaccharide (LPS) on the induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in muscularis resident macrophages of rat intestine in situ. When the tissue was incubated with LPS for 4 h, mRNA levels of iNOS and COX-2 were increased. The majority of iNOS and COX-2 proteins appeared to be localized to the dense network of muscularis resident macrophages immunoreactive to ED2. LPS treatment also increased the production of nitric oxide (NO), PGE(2), and PGI(2). The increased expression of iNOS mRNA by LPS was suppressed by indomethacin but not by N(G)-monomethyl-L-arginine (L-NMMA). The increased expression of COX-2 mRNA by LPS was affected neither by indomethacin nor by L-NMMA. Muscle contractility stimulated by 3 microM carbachol was significantly inhibited in the LPS-treated muscle, which was restored by treatment of the tissue with L-NMMA, aminoguanidine, indomethacin, or NS-398. Together, these findings show that LPS increases iNOS expression and stimulates NO production in muscularis resident macrophages to inhibit smooth muscle contraction. LPS-induced iNOS gene expression may be mediated by autocrine regulation of PGs through the induction of COX-2 gene expression.

Effect of Tamoxifen on Transforming Growth Factor β1Production by Keloid and Fetal Fibroblasts

BACKGROUND

Evidence suggests that keloid scar formation may be mediated, in part, by deranged growth factor activity, including that of transforming growth factor (TGF) beta1. Tamoxifen citrate has shown promise in the treatment of keloids.

OBJECTIVE

To evaluate the effect of tamoxifen on autocrine growth factor expression in keloid and fetal dermal fibroblasts, which exhibit scar-free healing.

DESIGN

Serum-free cell lines of keloid and fetal dermal fibroblasts were established. Cell cultures were exposed to different concentrations of tamoxifen solution (8 and 12 or 16 micromol/L). Cell counts were performed and supernatants collected at 24, 48, and 96 hours. Cell-free supernatants were quantitatively assayed for TGF-beta1 expression.

RESULTS

Keloid fibroblasts show increased per-cell TGF-beta1 production compared with fetal fibroblasts. Tamoxifen appeared to decrease per-cell TGF-beta1 production at each of the time points evaluated.

CONCLUSIONS

Keloids likely arise due to locally insufficient or excessive concentrations of specific growth factors. The higher level of TGF-beta1 produced by keloid cells compared with fetal fibroblasts could be related to the aberrant wound healing seen with keloids. The addition of tamoxifen may lead to improved wound healing in keloids by decreasing the expression of TGF-beta1.

Impaired degradation of serum amyloid A (SAA) protein by cytokine-stimulated monocytes

Secondary amyloidosis (AA amyloidosis) is a systemic disease characterized by the extracellular tissue deposition of insoluble amyloid A (AA) protein. Aberrant metabolism of serum amyloid A (SAA) by macrophages is only one of many putative mechanisms which may be important in AA amyloidogenesis. In this study, we investigated the effects of cytokines on human monocyte-mediated SAA proteolysis. Human peripheral blood mononuclear cells (PBMC) or CD14(+) monocytes were cultured with SAA, and the culture supernatants were then subjected to anti-SAA immunoblot. CD14(+) monocytes degraded SAA completely. Whereas, when CD14(+) monocytes were pretreated with IL-1 beta or IFN-gamma, increasing amounts of SAA-related derivatives were detected in culture supernatants. These findings suggest that activation of monocytes by IL-1 beta or IFN-gamma hampers the proteolysis of a precursor protein and leads to a partial degradation of SAA. This down-regulated proteolysis of SAA protein by cytokine-stimulated monocytes may play a role in the mechanism of AA amyloid formation as well as its removal.

Lack of effect of the abnormal fatty acid metabolism in NC/Nga mice on their atopic dermatitis

Although clinical evidence has suggested that dysregulated fatty acid metabolism is associated with atopic disorders, the molecular basis for such a correlation remains to be demonstrated. In the present study, we analyzed the fatty acid composition in peripheral blood cells of NC/Nga mice, a model for atopic dermatitis (AD). We found that arachidonic acid significantly accumulated in mice with the AD manifestation. In addition, the leucotriene B4-releasing ability upon calcium ionophore A23187 stimulation was potentiated in blood cells. An arachidonic acid accumulation was not apparent in the non-atopic BALB/c strain, but was still observed in healthy NC/Nga mice fed under specific pathogen-free conditions. These results indicate that a disturbed fatty acid metabolism in NC/Nga mice was not a trigger factor for their dermatitis development.

Pregnancy and murine thyroiditis: thyroglobulin immunization leads to fetal loss in specific allogeneic pregnancies

Thyroid autoantibodies are risk factors in human pregnancy. To investigate the influence of autoimmune thyroiditis on pregnancy, we have studied the impact of murine experimental autoimmune thyroiditis (EAT) on pregnancy outcome by using thyroglobulin (Tg) immunized CBA/J (H2(k)) female mice. When Tg immunized mice were mated with BALB/c (H2(d)) males, only 57% (47/83) of pregnant mice maintained their conceptions compared with >85% of other strain combinations (P < 0.05). We also found that MHC class II antigens were expressed on placental cells from Tg immunized pregnant mice but not in control normal pregnancies. Furthermore, the frequency and severity of thyroiditis, assessed by histological analyses, was also increased in Tg immunized mice mated with the BALB/c strain compared with syngeneic pregnancies (P < 0.05). In these pregnant mice mated with BALB/c, interleukin-4 secretion by mitogen-stimulated spleen cells was significantly suppressed and interferon-gamma secretion by mixed lymphocyte reactions with BALB/c cells was significantly increased. These data demonstrated enhanced Th1 cell proliferation and fetal loss in CBA/J X BALB/c pregnancies. We concluded, therefore, that pregnancy loss was increased in experimental autoimmune thyroiditis in a manner that was dependent on paternal antigens. These observations have broad implications for understanding the immunology of pregnancy.

Effects of nitric oxide on matrix metalloproteinase-2 production by rheumatoid synovial cells

Nitric oxide (NO) is a multifunctional messenger molecule generated from L-arginine by a family of enzymes, including nitric oxide synthase (NOS). This study was performed to examine whether NO modulates the production of matrix metalloproteinases (MMPs), which degrade all components of extracellular matrix (ECM), in rheumatoid synovial cells. We investigated the effects of exogenously generated NO by a NO donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP), on the MMPs production by rheumatoid synovial cells. Culture media conditioned by SNAP-treated synovial cells were examined by gelatin zymography and immunoblot analysis. Incubation of synovial cells with SNAP resulted in gelatinase A production in a dose-dependent fashion. Furthermore, RT-PCR analysis demonstrated that MMP-2 mRNA expression was induced in SNAP-treated synovial cells. In contrast, SNAP did not influence the production of TIMP-1 and TIMP-2, which preferentially inhibit MMP-2, by rheumatoid synovial cells. Our data indicate that NO could modulate MMP production by rheumatoid synovial cells and therefore contribute to ECM degradation of articular components in RA.

Magnetization transfer ratio in new MS lesions before and during therapy with IFNbeta-1a

OBJECTIVE

The authors examined the effect of 6.0 MIU interferon beta-1a (IFNbeta-1a) administered IM each week on the evolution of monthly magnetization transfer ratio (MTR) within new gadolinium-enhancing (Gd+) lesions in patients with very early relapsing-remitting (RR) MS.

BACKGROUND

IFNbeta is an effective disease-modifying treatment for patients with RRMS. Among other effects, it has been shown to decrease the number of new Gd+ and T2-weighted lesions. MTR is a putative marker for irreversible tissue damage and evolution of MTR within a lesion may reflect recovery of tissue damage. It is not known whether IFNbeta-1a affects the recovery phase of lesions.

METHODS

Eight untreated patients with RRMS who completed up to 14 monthly brain MRI sessions elected to initiate treatment with IFNbeta-1a. Four out of eight patients developed new Gd+ lesions during treatment. MTR of lesions at the time of appearance and subsequent rate of change of monthly MTR were compared before and after treatment (stratified Mann-Whitney test).

RESULTS

The difference between MTR at appearance of 47 new Gd+ lesions before treatment versus 23 new Gd+ lesions during treatment was not significant. Twenty-two of 47 new Gd+ lesions before treatment and 11 of 23 new Gd+ lesions after treatment were monitored for up to 6 months. After appearance of new Gd+ lesions, the rate of increase in MTR was faster during therapy (p = 0.037).

CONCLUSION

MTR abnormalities within new Gd+ lesions evolve at a faster rate during treatment with IFNbeta-1a than before initiating therapy. This is consistent with the hypothesis that IFNbeta-1a promotes resolution of new Gd+ lesions.

Changes in the levels of mRNAs for putative cell growth-related genes in the albedo and flavedo during citrus fruit development

 Changes in mRNA levels for the seven gene homologues to endoxyloglucan transferase-related protein, expansin, extensin, β-1,3 glucanase, glycine-rich protein, pectinacetylesterase and pectinesterase, which were obtained by random sequencing studies, were investigated in relation to rind development in citrus (Citrus unshiu Marc.) fruit. Expression patterns in the albedo and flavedo were classified into four types: Type-I, transcript levels low in early fruit development but increased at the ripening stage; Type-II, transcript levels high until mid-development and then decreased towards ripening; Type-III, detectable transcript limited to fruitlets at 26 days after flowering (DAF); Type-IV, ubiquitous during the development. Based on the expression patterns, we discuss the possible roles of these genes in rind development.

Expression of IFN-gamma in cerebrovascular endothelial cells from aged mice

Recently, it has become clear that interferon-gamma (IFN-gamma) plays a role in the central nervous system (CNS) as well as in the immune system. However, the reason for the alteration in IFN-gamma production in the brain with aging remains unknown. In this study, we investigated the expression of IFN-gamma in the brain in terms of both mRNA and protein and compared the expression in young adult brain with that in aged mice. The cerebrum and cerebellum were collected from young adult (8-10 weeks old) and aged (24-26 months old) BALB/c mice, and the expressions of IFN-gamma and IFN-gamma receptor-1 (IFNGR-1) mRNA were examined by RT-PCR. Expression of IFN-gamma mRNA was detected in the brains from aged mice but not in those from young adult mice. However, IFNGR-1 mRNA was expressed in the brains from both young adult and aged mice. Moreover, IFN-gamma levels in the cerebrum and cerebellum from aged mice were detectable by ELISA, but IFN-gamma was undetectable in these tissues from young adult mice. To identify the cellular source of IFN-gamma in the brain of aged mice, immunostaining using antimouse IFN-gamma monoclonal antibody (mAb) was done. Immunoreactivity of IFN-gamma appeared to be located in cerebrovascular endothelial cells, including the choroid plexus of the cerebellum from aged mice. Expression of IFN-gamma and IFNGR-1 was also identified in isolated microvessels from brains. These results suggest that IFN-gamma plays a role in age-associated changes.

Molecular cloning and characterization of a novel gene encoding limonoid UDP-glucosyltransferase in Citrus

We isolated a cDNA clone encoding limonoid UDP-glucosyltransferase (limonoid GTase) from the albedo of Satsuma mandarin (Citrus unshiu Marc.) and investigated the contribution to limonoid glucoside accumulation in fruit. The isolated cDNA clone (CitLGT) was 1732 bp in length encoding 511 deduced amino acids with a predicted molecular mass of 57.5 kDa. The products of in vitro translation from an expression vector had the limonoid GTase activity. Southern blot analysis of genomic DNA indicated that CitLGT was present as a single copy gene in the Citrus genome. The amount of transcript corresponding to CitLGT mRNA changed the same way as the fluctuation of limonin glucoside content during fruit development of navel orange (Citrus sinensis Osb.). This indicates that the transcription of CitLGT regulates the conversion of limonoid aglycones to glucosides in citrus fruit.

Regulation of rheumatoid synovial cell growth by ceramide

Overgrowth of rheumatoid synoviocytes, which results in joint destruction, is due to impaired balance between cell proliferation and cell death (apoptosis). Ceramide is an important lipid messenger involved in mediating a variety of cell functions including apoptosis. We investigated the effects of ceramide on growth-promoting anti-apoptotic signals in rheumatoid synovial cells. Human synovial cells isolated from patients with rheumatoid arthritis (RA) were stimulated with platelet-derived growth factor (PDGF) in the presence or absence of C2-ceramide. The kinase activity of Akt, MEK, and ERK1/2 was analyzed in PDGF-stimulated synovial cells by Western blot analysis. Pretreatment with C2-ceramide completely inhibited PDGF-induced cell cycle progression of rheumatoid synovial cells. PDGF stimulation induced phosphorylation and activation of Akt, MEK, and ERK1/2 in rheumatoid synovial cells. C2-ceramide inhibited the activation of Akt, MEK and ERK1/2 in PDGF-stimulated synovial cells. Our data demonstrated that inhibition of anti-apoptotic kinases, such as Akt and ERK1/2, may play an important role in ceramide-mediated apoptosis of rheumatoid synovial cells.