Reduced expression of the regulatory CD4+ T cell subset is related to Th1/Th2 balance and disease severity in rheumatoid arthritis

OBJECTIVE

To elucidate the involvement of the regulatory CD4+ T cells that produce high levels of interleukin-10 (IL-10) and low levels of IL-4 and IL-2 in the pathogenesis of rheumatoid arthritis (RA), we investigated whether the frequency of this type of CD4+ T cell subset in peripheral blood lymphocytes (PBL) or synovial lymphocyte infiltrates of patients with RA correlated with disease severity and histologic features in rheumatoid synovium.

METHODS

PBL and synovial lymphocyte infiltrates were isolated from peripheral blood samples and synovial tissues obtained from 25 patients with RA. Control specimens were obtained from 18 patients with osteoarthritis (OA) and 10 patients with traumatic injuries of the knee joint. CD4+ T cell subsets were categorized as Th1 (production of interferon-gamma [IFNgamma], but not IL-4), Th2 (production of IL-4, but not IFNgamma), or CD4+ T cell subsets producing IL-10, IL-2, or IL-4. The percentages of these T helper subsets among PBL and among synovial infiltrating lymphocytes were determined by an intracellular staining assay with flow cytometric analysis.

RESULTS

The level of expression of CD4+ T cells producing IL-10 but not IL-2 and IL-4 in the peripheral blood and synovial tissue was significantly lower in RA patients than in OA patients and trauma patients. In RA patients, the frequency of this type of CD4+ T cell subset among synovial infiltrating CD4+ T cells was inversely correlated with the frequency of Th1 cells and the Th1/Th2 balance in synovial lymphocytes, serum C-reactive protein value, disease activity score, and the degree of synovial lining hyperplasia and lymphocyte infiltration in rheumatoid synovium. There was a reciprocal relationship between the frequency of Thl cells and CD4+ T cells producing IL-10 but not IL-2 and IL-4 in the peripheral blood of RA patients.

CONCLUSION

In RA, reduced expression of the CD4+ T cell subset producing IL-10 but not IL-2 and IL-4 may be responsible for the dominance of Th1 over Th2 cells at sites of inflamed synovium and in the peripheral blood. Decreases in this type of CD4+ T cell subset may induce the down-regulation of T cell tolerance and exacerbate the inflammatory process in RA.

Tumor necrosis factor-alpha-mediated signal transduction in human neutrophils: involvement of sphingomyelin metabolites in the priming effect of TNF-alpha on the fMLP-stimulated superoxide production

We investigated the mechanism underlying the priming effect of TNF-alpha on fMLP-stimulated superoxide production in human neutrophils. TNF-alpha enhanced fMLP-stimulated superoxide production in a concentration-dependent manner. TNF-alpha also induced sphingomyelin (SM) hydrolysis and increased the formation of its metabolite, sphingosine-1-phosphate (SP-1-P). The treatment of neutrophils with sphingomyelinase also resulted in a similar priming effect. C2 ceramide produced a concentration-dependent inhibition of fMLP-stimulated superoxide production within the concentration range of 1-30 microM. Sphingosine had a dual effect on fMLP-stimulated superoxide generation, exhibiting a priming effect at lower concentrations (0.2-1 microM), but an inhibitory effect at higher concentrations (1-30 microM). SP-1-P (1-30 microM), showed a concentration-dependent enhancement of fMLP stimulated superoxide production. Furthermore, after treating neutrophils with DL-threo-dihydro-sphingosine, a competitive inhibitor of sphingosine kinase, TNF-alpha produced a similar dual effect as observed with sphingosine. These results strongly suggest that SM hydrolysis plays a key role in the intracellular signal transduction mediating the TNF-alpha-mediated priming effect.

p38 MAP kinase is required for vasopressin-stimulated HSP27 induction in aortic smooth muscle cells

We previously showed that arginine vasopressin (AVP) stimulates heat shock protein 27 (HSP27) induction through protein kinase C activation in aortic smooth muscle A10 cells. In the present study, we examined whether the mitogen-activated protein (MAP) kinase superfamily is involved in the AVP-stimulated HSP27 induction in A10 cells. AVP stimulated the phosphorylation of p42/p44 MAP kinase and p38 MAP kinase. On the contrary, AVP had little effect on SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase) phosphorylation. The HSP27 accumulation by AVP was not affected by PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. SB203580 and PD169316, specific inhibitors of p38 MAP kinase, suppressed the AVP-induced accumulation of HSP27. 12-O-tetradecanoylphorbol 13-acetate, an activator of protein kinase C, induced accumulation of HSP27 and was not inhibited by PD98059 but was inhibited by SB203580. Calphostin C and ET-18-OCH(3), inhibitors of protein kinase C, reduced the phosphorylation of p38 MAP kinase by AVP. SB203580 and PD169316 suppressed the AVP-increased levels in mRNA for HSP27. Dissociation of the aggregated HSP27 to the dissociated HSP27 was induced by AVP. These results strongly suggest that p38 MAP kinase takes part in the pathway of the AVP-stimulated induction of HSP27 in vascular smooth muscle cells.

Measurement of furancarboxylic acid, a candidate for uremic toxin, in human serum, hair, and sweat, and analysis of pharmacological actions in vitro

3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), a candidate for uremic toxin, was measured in human hair for examining a possible utility as indicator of renal dysfunction. The serum concentration of CMPF was much higher (32.3 +/- 2.7 microg/ml, n = 17; mean +/- SEM) in uremic patients aged 40-55 years receiving hemodialysis treatment than in healthy younger subjects (3.61 +/- 0.19 microg/ml, n = 22), aged 18-23 years. However, the hair concentration of CMPF tended to be lower in the patients (6.8 +/- 1.7 ng/10 mg hair) than in the healthy younger subjects (15.8 +/- 4.5 ng/10 mg) and was significantly lower than that in the healthy age-matched subjects (22.4 +/- 5.3 ng/10 mg, n = 12), aged 40-47 years. Since CMPF was measurable in the sweat (4.4 +/- 3.7 ng/mg) collected from six out of seven healthy subjects examined, it was suggested that the contribution of sweat to the measurement of CMPF in hair was considerable. The fact that the uremic patients undergoing hemodialysis therapy had less sweat than healthy subjects may explain the lower concentration of CMPF in the patients' hair. The pathophysiological roles of CMPF in the body were attempted to be explored by using excised guinea pig organs, and human platelets and neutrophils. CMPF showed no remarkable effects in the concentration range of < or =10(-4) M except for only slight suppression of spontaneous contracture of guinea pig tenia coli at 10(-4) M. As far as the organs and tissues examined in the present study are concerned, the biological activity of CMPF itself, if any, may be very weak. Precaution should be taken against the delivery of a substance through sweat to hair when a small amount of substance is attempted to be measured in hair by employing a sensitive analytical method.

Involvement of p42/p44 mitogen-activated protein kinase in prostaglandin f(2alpha)-stimulated induction of heat shock protein 27 in osteoblasts

We previously reported that prostaglandin F(2alpha) (PGF(2alpha)) activates both phosphoinositide-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D in osteoblast-like MC3T3-E1 cells and then induces the activation of protein kinase C (PKC). In this study, we investigated the effect of PGF(2alpha) on the induction of heat shock protein 27 (HSP27), a low-molecular-weight heat shock protein, in these cells. PGF(2alpha) significantly induced the accumulation of HSP27 dose-dependently within the range of 10 nM to 10 microM. PGF(2alpha) stimulated the increase in the levels of mRNA for HSP27. A total of 10 nM 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of PKC, induced the accumulation of HSP27. The stimulative effect of PGF(2alpha) was reduced in the PKC down-regulated cells. Calphostin C, a specific inhibitor of PKC, suppressed the PGF(2alpha)-induced HSP27 accumulation as well as that induced by TPA. HSP27 induction by PGF(2alpha) was reduced by U-73122, a phospholipase C inhibitor, or propranolol, a phosphatidic acid phosphohydrolase inhibitor. PGF(2alpha) and TPA stimulated p42/p44 mitogen-activated protein (MAP) kinase. PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase, suppressed the induction of HSP27 stimulated by PGF(2alpha) or TPA. PD98059 and calphostin C reduced the levels of mRNA for HSP27 increased by PGF(2alpha). These results indicate that PGF(2alpha) stimulates the induction of HSP27 via p42/p44 MAP kinase activation, which depends on upstream PKC activation in osteoblasts.

Endothelin-1 stimulates heat shock protein 27 induction in osteoblasts: involvement of p38 MAP kinase

We previously reported that endothelin-1 (ET-1) activates p42/p44 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells and consequently induces synthesis of interleukin-6. In the present study, we investigated the effect of ET-1 on the induction of heat shock protein 27 (HSP 27) in MC3T3-E1 cells. ET-1 time and dose dependently stimulated HSP 27 accumulation. ET-1 induced an increase in the levels of mRNA for HSP 27. Both staurosporine and calphostin C, inhibitors of protein kinase C (PKC), suppressed the ET-1-induced HSP 27 accumulation. 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator, induced the HSP 27 accumulation and the expression of mRNA for HSP 27. The ET-1-stimulated HSP 27 accumulation was reduced in PKC-downregulated MC3T3-E1 cells. The HSP 27 accumulation by ET-1 was not suppressed by PD-98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. ET-1 or TPA induced the phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinase, reduced the ET-1-stimulated HSP 27 accumulation. Calphostin C and U-73122, a phospholipase C inhibitor, suppressed the ET-1-induced phosphorylation of p38 MAP kinase. U-73122 and propranolol, a phosphatidic acid phosphohydrolase inhibitor, reduced the ET-1-stimulated HSP 27 accumulation. SB-203580 suppressed the ET-1-stimulated increase in the mRNA levels for HSP 27. These results strongly suggest that ET-1 stimulates HSP 27 induction in osteoblasts and that p38 MAP kinase activation is involved in the HSP 27 induction.

Sphingosine 1-phosphate induces heat shock protein 27 via p38 mitogen-activated protein kinase activation in osteoblasts

We previously showed that sphingosine 1-phosphate acts as a second messenger for tumor necrosis factor alpha-induced interleukin-6 synthesis in osteoblast-like MC3T3-E1 cells and that the synthesis by sphingosine 1-phosphate is dependent on p42/p44 mitogen-activated protein (MAP) kinase activation. In the present study, we investigated the effect of sphingosine 1-phosphate on the induction of heat shock protein 27 (HSP27) in MC3T3-E1 cells. Not C2-ceramide, but sphingosine and sphingosine 1-phosphate significantly induced HSP27 accumulation dose dependently in the range between 1microM and 30 microM. DL-threo-dihydrosphingosine, an inhibitor of sphingosine kinase, markedly inhibited the sphingosine-induced HSP27 accumulation. Sphingosine 1-phosphate induced increase in the levels of the mRNA for HSP27. Sphingosine 1-phosphate stimulated the phosphorylation of p38 MAP kinase. The sphingosine 1-phosphate-induced HSP27 accumulation was dose dependently suppressed by SB203580, an inhibitor of p38 MAP kinase, but not PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. SB203580 reduced the sphingosine 1-phosphate-induced increase of mRNA for HSP27. These results strongly suggest that sphingosine 1-phosphate-stimulated HSP27 induction is mediated via p38 MAP kinase activation in osteoblasts.

Dominant and shared T cell receptor beta chain variable regions of T cells inducing synovial hyperplasia in rheumatoid arthritis

Previously, we demonstrated the presence of at least two distinct subpopulations of patients with rheumatoid arthritis (RA) employing a cell-transfer experiment using severe combined immunodeficient (SCID) mice. One group of patients, whose T cells derived from the rheumatoid joints, induced synovial hyperplasia (SH) in the SCID mice (the positive group). The other group did not display the induction of SH (the negative group). TCR/Vbeta gene usage analysis indicated that some dominant T cell subpopulations were oligoclonally expanding only in the rheumatoid joints, and not in the periphery of the patients of the positive group. Moreover, these T cell subpopulations were not seen in the joints of patients in the negative group or in non-RA patients. In addition, the preferential uses of certain TCR/Vbetas (Vbeta8, Vbeta12, Vbeta13, and Vbeta14) genes were demonstrated in these T cells. In this study, to investigate whether these T cells are driven by a certain antigen(s), the third complementarity determining regions (CDR3s) of TCR/Vbeta, especially Vbeta8 and Vbeta14 PCR products, were cloned and sequenced. As a result, a dominant CDR3 sequence, CASS-PRERAT-YEQ, was found in Vbeta14+ T cells from the rheumatoid joint of a patient (Patient 1) of the positive group with a Vbeta14 skew. The identical CDR3 sequence also predominated in Vbeta14+ T cells from the rheumatoid joint of another patient (Patient 7) of the positive group with a Vbeta14 skew. In addition, in the patients (Patients 4, 7, 8) of the positive group with a Vbeta8 skew, other dominant CDR3 sequences, CASS-ENS-YEQ and CASS-LTEP-DTQ, were found as in the case of Vbeta14. However, no identical CDR3 sequences were detected dominantly in the joints of the patients in the negative group or in non-RA patients. A Vbeta14+ T cell clone (TCL), named G3, with the identical CDR3 sequence, CASS-PRERAT-YEQ, was isolated successfully from Patient 1, and cell transfer of G3 with autologous irradiated peripheral mononuclear cells induced SH in the SCID mice. Taken together, these results suggest that T cells inducing SH, thought to be pathogenic for RA, might be driven by a certain shared antigen(s).

Involvement of p38 mitogen-activated protein kinase in basic fibroblast growth factor-induced interleukin-6 synthesis in osteoblasts

We previously showed that basic fibroblast growth factor (bFGF)-induced activation of protein kinase C (PKC) via phosphatidylinositol-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D suppresses interleukin-6 (IL-6) synthesis by bFGF itself in osteoblast-like MC3T3-E1 cells. In the present study, we further investigated the mechanism underlying the bFGF-induced IL-6 synthesis in MC3T3-E1 cells. bFGF time-dependently induced the phosphorylation of p38 mitogen-activated protein (MAP) kinase. SB203580, a specific inhibitor of p38 MAP kinase, suppressed the bFGF-induced IL-6 synthesis dose-dependently. The phosphorylation of p38 MAP kinase by bFGF was suppressed by TMB-8, an inhibitor of intracellular Ca(2+) mobilization, or the depletion of extracellular Ca(2+) with EGTA. A23187, a Ca-ionophore, stimulated the phosphorylation of p38 MAP kinase. SB203580 inhibited the A23187-induced synthesis of IL-6. 1-Oleoyl-2-acetyl-sn-glycerol, a synthetic diacylglycerol activating PKC, reduced the bFGF-induced IL-6 synthesis. 12-O-Tetradecanoylphorbol-13-acetate, an activator of PKC, attenuated the phosphorylation of p38 MAP kinase by bFGF, but did not affect the A23187-induced phosphorylation. These results strongly suggest that bFGF-induced IL-6 synthesis is mediated via p38 MAP kinase activation in osteoblasts, and that PKC acts at a point upstream from p38 MAP kinase.

Sphingosine 1-phosphate regulates heat shock protein 27 induction by a p38 MAP kinase-dependent mechanism in aortic smooth muscle cells

In an aortic smooth muscle cell line, A10 cells, we investigated the effect of sphingosine 1-phosphate on the induction of heat shock protein 27 (HSP27), a low-molecular-weight heat shock protein. Sphingosine 1-phosphate significantly induced the accumulation of HSP27 in a pertussis toxin-sensitive manner. The effect was dose-dependent in the range between 0.1 and 30 microM. Sphingosine 1-phosphate stimulated an increase in the levels of mRNA for HSP27. Sphingosine 1-phosphate stimulated both p42/p44 mitogen-activated protein (MAP) kinase and p38 MAP kinase activation. PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase, did not affect sphingosine 1-phosphate-stimulated HSP27 induction. In contrast, SB203580, an inhibitor of p38 MAP kinase, reduced sphingosine 1-phosphate-induced HSP27 induction. SB203580 reduced the levels of mRNA for HSP27 induced by sphingosine 1-phosphate. These results indicate that sphingosine 1-phosphate stimulates the induction of HSP27 via p38 MAP kinase activation in aortic smooth muscle cells.

Structure and enzymatic properties of genetically truncated forms of the water-insoluble glucan-synthesizing glucosyltransferase from Streptococcus sobrinus

Glucosyltransferase-I (GTF-I: 175 kDa) of a cariogenic bacterium, Streptococcus sobrinus 6715, mediates the conversion of water-soluble dextran (alpha-1,6-glucan) into a water-insoluble form by making numerous alpha-1,3-glucan branches along the dextran chains with sucrose as the glucosyl donor. The structures and catalytic properties were compared for two GTF-I fragments, GTF-I' (138 kDa) and GS (110 kDa). Both lack the N-terminal 84 residues of GTF-I. While GTF-I' still contains four of the six C-terminal repeats characteristic of streptococcal glucosyltransferases, GS lacks all of them. Electron microscopy of negatively stained samples indicated a double-domain structure for GTF-I', consisting of a spherical head with a smaller spherical tail, which was occasionally seen as a long extension. GS was seen just as the head portion of GTF-I'. In the absence of dextran, both fragments simply hydrolyzed sucrose with similar K(m) and k(cat) values at low concentrations (<5 mM). At higher sucrose concentrations (>10 mM), however, GTF-I' exhibited glucosyl transfer activity to form insoluble alpha-1, 3-glucans. So did GS, but less efficiently. Dextran increased the rate and efficiency of the glucosyl transfer by GTF-I'. On removal of the C-terminal repeats of GTF-I' by mild trypsin treatment, this dextran-stimulated transfer was completely lost and the dextran-independent transfer became less efficient. These results indicate that the N-terminal two-thirds of the GTF-I sequence are organized as a structurally and functionally independent domain to catalyze not only sucrose hydrolysis but also glucosyl transfer to form alpha-1,3-glucan chains, although not efficiently; the C-terminal repeat increases the efficiency of the intrinsic glucosyl transfer by the N-terminal domain as well as rendering the whole molecule primer-dependent for far more efficient insoluble glucan synthesis.

Comparative antiplatelet effects of aspirin, vapiprost and GR144053, a GPIIb/IIIa antagonist, with a special reference to the role of platelet microaggregates

Microthrombi produced have a potential to form larger thrombi, leading to vascular occlusions. Recently, a new device to easily detect microaggregates using laser-light scattering (LS) has been developed. We adopted this device to comparatively evaluate the inhibitory effects of aspirin (1,3 or 10 mg kg(-1)), vapiprost (0.3, 1 or 3 mg kg(-1)) or GR144053 (0.1, 0.3 or 1 mg kg(-1)) on ex vivo aggregation of hamster platelets in relation to their in vivo antithrombotic effects. A transluminal thrombus was produced in the hamster femoral artery by the photochemical reaction. Each compound was injected i.v. as a bolus 10 min prior to the reaction, showing a dose-dependent antithrombotic effect, i.e. they prolonged the time before the artery occluded. At that time cyclic flow reductions occurred more marked when aspirin or vapiprost was given. At the end of experiments, blood was collected to evaluate the platelet aggregation using both the new LS device and the conventional optical density (OD) method. Many more small aggregates were still formed when the highest dose of aspirin or vapiprost was used as compared with that of GR144053, although suppression of the platelet aggregation using the OD method, prolongation of the occlusion time and the bleeding time were quite similar. In conclusion, a GPIIb/IIIa antagonist markedly suppressed the microthrombi and reduced the cyclic flow reduction. This further indicates the importance of small aggregates as triggers of thrombosis and shows that prevention of their formation may result in improved vascular patency after thrombotic insult.

Comparison of the antithrombotic effects and bleeding risk of fractionated aurin tricarboxylic acid and the GPIIb/IIIa antagonist GR144053 in a hamster model of stenosis

The present study compared the antithrombotic properties of fractionated aurin tricarboxylic acid (ATA), an inhibitor of platelet glycoprotein (GP) Ib, and GR144053, a GPIIb/IIIa antagonist, in a hamster model of stenosis. Endothelial cell injury in the hamster carotid artery was achieved by a 2F modified catheter. Arterial blood flow in the control groups was interrupted 5.4+/-0.9 minutes after the injury. When ATA (0.01, 0.03, 0.1, 0.3, and 1.0 mg/kg per hour) or GR144053 (0.1, 0.3, and 1.0 mg/kg per hour) were continuously infused intravenously, the time elapse before the vessel completely occluded was prolonged in a dose-dependent manner. However, all arteries in the ATA-treated groups ultimately occluded during the observation period even if the aggregation of platelets ex vivo and induced by botrocetin was completely inhibited. When either ATA (0.1 mg/kg per hour) or GR144053 (0.3 mg/kg per hour) were infused via an implanted osmotic pump together with tissue-type plasminogen activator (tPA), late patency of the reperfused artery was improved compared to that of arteries treated with TPA alone. However, the cyclic reflow pattern after reperfusion on days 0 and 1 was not reduced by the ATA treatment. The bleeding time was significantly prolonged when either ATA or GT144053 was coadministered with tPA. The treatment with ATA showed an especially marked prolongation of the bleeding time. In conclusion, both inhibition of platelet activation by ATA or GR144053 prevent arterial thrombosis and enhance the thrombolytic effect of tPA, but GR144053 was more protective in its antithrombotic effect and more effective during thrombolytic therapy than ATA.

Activation of progelatinase B in synovial fluids of patients with rheumatoid arthritis, with reference to stromelysin-1 and tissue inhibitor of matrix metalloproteinase-1

OBJECTIVE

To clarify whether stromelysin-1 and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) are involved in the modulation of activation of progelatinase B in the synovial fluid of patients with rheumatoid arthritis (RA).

METHODS

Gelatinases in the synovial fluid of patients with RA were analyzed by gelatin zymography. Concentrations of stromelysin-1 and TIMP-1 were measured using a specific sandwich enzyme linked immunosorbent assay.

RESULTS

Forty-three rheumatoid synovial fluids containing progelatinase B were examined to clarify whether the enzyme was activated by incubation. Incubation at 37 degrees C caused the conversion of progelatinase B to the active form in 22 of the 43 synovial fluids. The levels of both stromelysin-1 and TIMP-1 were determined for each group and the concentration ratio of stromelysin-1/TIMP-1 in the synovial fluids of each group was highly correlated to the activation of progelatinase B.

CONCLUSION

The balance between the concentrations of stromelysin-1 and of TIMP-1 in the synovial fluid appears to determine whether the progelatinase B molecule causes conversion into the active form.

Inhibition of tumor necrosis factor-alpha induced neutrophil apoptosis by cyclic AMP: involvement of caspase cascade

Treatment of neutrophils with tumor necrosis factor-alpha (TNF-alpha) in the presence of cycloheximide induced apoptosis within 3 h, as evaluated by the occurrence of morphological nuclear changes characteristic of apoptosis. Pretreatment of neutrophils with dibutyryl cyclic AMP (dbcAMP) suppressed the TNF-alpha/cycloheximide-induced apoptosis in neutrophils in a concentration-dependent manner, while dbcAMP by itself did not induce any morphological changes. Forskolin, or a phosphodiesterase inhibitor, also produced a concentration-dependent inhibition on apoptosis. This inhibition by dbcAMP was completely reversed by pretreatment with the protein kinase A inhibitor, N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline sulphonamide (H-89). DbcAMP also inhibited the TNF-alpha/cycloheximide-induced activation of caspase-3, but it had no effect on the activation of caspase-8 in human neutrophils. Furthermore, dbcAMP did not directly inhibit activated caspase-3 activity. Inhibitor of protein kinase C, phosphatidylcholine-specific phospholipase C, tyrosine kinase, nitric oxide synthase, or granulocyte colony-stimulating factor or granulocyte monocyte colony-stimulating factor did not affect apoptosis. These results indicate that the elevation of levels of endogenous intracellular cyclic AMP and subsequent activation of protein kinase A play a crucial role in the prevention of apoptosis triggered by TNF-alpha/cycloheximide in human neutrophils, and that the possible target of cyclic AMP is a product in the metabolic pathway between caspase-8 and caspase-3.

Differential role of components of the fibrinolytic system in the formation and removal of thrombus induced by endothelial injury

The role of fibrinolytic system components in thrombus formation and removal in vivo was investigated in groups of six mice deficient in urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), or plasminogen activator inhibitor-1 (PAI-1) (u-PA-/-, t-PA-/- or PAI-1-/-, respectively) or of their wild type controls (u-PA+/+, t-PA+/+ or PAI-1+/+). Thrombus was induced in the murine carotid artery by endothelial injury using the photochemical reaction between rose bengal and green light (540 nm). Blood flow was continuously monitored for 90 min on day 0 and for 20 min on days 1, 2 and 3. The times to occlusion after the initiation of endothelial injury in u-PA+/+, t-PA+/+ or PAI-1+/+ mice were 9.4+/-1.3, 9.8+/-1.1 or 9.7+/-1.6 min, respectively. u-PA-/- and t-PA-/- mice were indistinguishable from controls, whereas that of PAI-1-/- mice were significantly prolonged (1 8.4+/-3.7 min). Occlusion persisted for the initial 90 min observation period in 10 of 18 wild type mice and was followed by cyclic reflow and reocclusion in the remaining 8 mice. At day 1, persistent occlusion was observed in 1 wild type mouse, 8 mice had cyclic reflow and reocclusion and 9 mice had persistent reflow. At day 2, all injured arteries had persistent reflow. Persistent occlusion for 90 min on day 0 was observed in 3 u-PA-/-, in all t-PA-/- mice at day 1 and in 2 of the t-PA-/-mice at day 2 (p <0.01 versus wild type mice). Persistent patency was observed in all PAI-1-/- mice at day 1 and in 5 of the 6 u-PA-/- mice at day 2 (both p <0.05 versus wild type mice). In conclusion, t-PA increases the rate of clot lysis after endothelial injury, PAI-1 reduces the time to occlusion and delays clot lysis, whereas u-PA has little effect on thrombus formation and spontaneous lysis.

Dissolution of nickel and tissue response observed by X-ray scanning analytical microscopy

The recently developed X-ray scanning analytical microscope (XSAM) was applied for the analysis of the soft tissue of rat in which Ni was implanted and serious inflammation occurred. Our aim is to investigate the relationship between tissue response and elemental distributions. The XSAM observation was conducted in air without pretreatment and staining of samples. Mapping images of P, S, Ca, Fe and Ni, which were the elements with low concentration in soft tissue, were obtained from the soft tissue blocks of rat where Ni was implanted. S mapping image showed the localization of S in muscle and in hairs. Ca mapping image showed the localization of Ca in muscle and hair roots. Fe distribution was also observed and the localized area was consistent with the hemorrhagic area. The Ni dissolution area was clearly detected around the Ni implant. Comparison with the histological observation showed that the Ni dispersed area was consistent with the inflammatory area and the degree of tissue damage was closely related to the dissolved Ni concentration.

Involvement of p42/p44 MAP kinase in endothelin-1-induced interleukin-6 synthesis in osteoblast-like cells

We previously reported that endothelin-1 induces synthesis of interleukin-6 (IL-6) via activation of protein kinase C in osteoblast-like MC3T3-E1 cells. In the present study, we further investigated whether p42/p44 mitogen-activated protein (MAP) kinase is involved in endothelin-1-induced IL-6 synthesis in these cells. Endothelin-1 stimulated p42/p44 MAP kinase activation in a dose-dependent manner in the range between 0.1 nmol/L and 0.1 micromol/L. PD98059, a specific inhibitor of the upstream kinase that activates p42/p44 MAP kinase, suppressed endothelin-1-induced IL-6 synthesis as well as endothelin-1-activated p42/p44 MAP kinase. Both p42/p44 MAP kinase activation and IL-6 synthesis induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C-activating phorbol ester, were reduced by PD98059. Calphostin C, a highly specific inhibitor of protein kinase C, suppressed endothelin-1-stimulated p42/p44 MAP kinase activation as well as endothelin-1-induced IL-6 synthesis. These results strongly suggest that protein kinase C-dependent p42/p44 MAP kinase activation is involved in endothelin-1-induced IL-6 synthesis in osteoblast-like cells.

Different mechanisms of synovial hyperplasia in rheumatoid arthritis and pigmented villonodular synovitis: the role of telomerase activity in synovial proliferation

OBJECTIVE

To elucidate the involvement of telomerase activity in the pathogenesis of rheumatoid arthritis (RA) and pigmented villonodular synovitis (PVS).

METHODS

Peripheral blood lymphocytes (PBL), synovial infiltrating lymphocytes, and synoviocytes were isolated from peripheral blood samples and synovial tissue obtained from 18 patients with RA, 9 with PVS, 12 with osteoarthritis (OA), and 10 with knee joint trauma. Cellular telomerase activity was measured by the telomeric repeat amplification protocol assay. In RA patients, the telomerase activity level in synovial infiltrating lymphocytes was assessed for correlations with histologic features in rheumatoid synovium.

RESULTS

A high level of telomerase activity was detected in the PBL and synovial infiltrating lymphocytes from RA patients and in the synoviocytes from PVS patients, whereas the enzyme activity was expressed at a low-to-borderline level in the PBL and synovial lymphocytes from OA, PVS, and trauma patients and was absent in the synoviocytes from RA as well as OA and trauma patients. In RA patients, the telomerase activity level in synovial infiltrating lymphocytes was significantly correlated with the intensity of synovial lining hyperplasia, microvessel proliferation, lymphocyte infiltration, and percentage of synovial cells positive for proliferating cell nuclear antigen in rheumatoid synovium.

CONCLUSION

Telomerase activation in lymphocytes may provide insights into the progression of synovitis and synovial proliferation in RA. Moreover, the enzyme may be implicated in the proliferation of synoviocytes in PVS.

Synovitis in rheumatoid arthritis: scoring of characteristic histopathological features

Synovial tissue specimens obtained from the knee joints of 40 patients with rheumatoid arthritis (RA) and from 22 patients with osteoarthritis (OA) were examined histologically. The histopathological features of RA synovitis and OA synovitis were then compared. Seven criteria items of histopathological features characteristic to RA synovitis were given a score of 1-3 points each in order to evaluate the histological severity of the seven items. Their total scores were then calculated. A comparison of the total RA synovitis score and the total OA synovitis score revealed that RA synovitis showed more than 11 points (maximum 20 points), while OA synovitis showed less than 10 points in all but two cases. Furthermore, the total scores of RA synovitis were then determined in the same manner for other joints, where it was confirmed that five other joints had scores of more than 11 points as well; that is, the intercarpal, wrist, elbow, ankle and hip joints in 52 patients with RA. From these results, it was concluded that in the histological examination of biopsied synovial tissue of RA, if the total score for synovitis is more than 11 points (maximum 20 points), an histological diagnosis of RA synovitis can be confirmed.

Biochemical effect of intra-articular injections of high molecular weight hyaluronate in rheumatoid arthritis patients

OBJECTIVE

The purpose of this study was to analyze the biochemical characteristics of synovial fluids after treatment of patients with rheumatoid arthritis (RA) with intra-articularly injected hyaluronate (HA).

TREATMENT

In a double-blind study, 13 patients received intra-articular injections of 1% HA in phosphate buffered saline (PBS) while 13 other patients were injected 0.01% HA in PBS, as the control group. Injections were administered once a week for five weeks.

METHODS

Clinical efficacy and characteristics of synovial fluid were compared between groups.

RESULTS

Significant clinical improvement was observed in the HA-treated group compared to the control group. The viscosity of retained synovial fluid increased. Stringing and HA concentration increased significantly whereas the concentrations of protein and chondroitin sulfate 4 and 6 decreased significantly. The HA molecular weight remained the same in both groups.

CONCLUSION

Intra-articular HA injection altered the properties of synovial fluid and proved efficacious for patients with RA.

Vasopressin stimulates the induction of heat shock protein 27 and alphaB-crystallin via protein kinase C activation in vascular smooth muscle cells

In the present study, we examined the effect of vasopressin on the induction of the low-molecular-weight heat shock proteins heat shock protein 27 (HSP27) and alphaB-crystallin in an aortic smooth muscle cell line, A10 cells. Vasopressin induced a time-dependent accumulation of HSP27 and alphaB-crystallin. The stimulatory effects of vasopressin were dose-dependent over the range 0.1 nmol/L to 0.1 micromol/L. The EC50 values for vasopressin were 2 (HSP27) and 4 nmol/L (alphaB-crystallin). Vasopressin induced increases in the levels of the mRNAs for HSP27 and alphaB-crystallin. 12-O-Tetradecanoylphorbol 13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, induced an accumulation of HSP27 (EC50, 20 nmol/L) and alphaB-crystallin (EC50, 2 nmol/L). In contrast, 4alpha-phorbol 12,13-didecanoate, a non-PKC-activating phorbol ester, had no such effect. Staurosporine and calphostin C, inhibitors of PKC, significantly reduced the vasopressin-induced accumulation of HSP27 and alphaB-crystallin as well as that induced by TPA. BAPTA/AM and TMB-8, inhibitors of intracellular Ca2+ mobilization, significantly reduced the vasopressin-induced accumulation of HSP27 and alphaB-crystallin. These results strongly suggest that vasopressin stimulates the induction of HSP27 and alphaB-crystallin via PKC activation in vascular smooth muscle cells and that this effect of vasopressin is dependent on intracellular Ca2+ mobilization.