The difference in joint instability affects the onset of cartilage degeneration or subchondral bone changes.

OBJECTIVE: It has been debated whether the onset of knee osteoarthritis is initiated in cartilage or subchondral bone. The purpose of this study was to clarify the effects of increasing or decreasing joint instability on cartilage degeneration and subchondral bone changes in knee OA by comparing different models of joint instability. DESIGN: We used the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model. In addition, we created a controlled abnormal tibial translation (CATT) model and a controlled abnormal tibial rotation (CATR) model. We performed joint instability analysis, micro-computed tomography analysis, histological and immunohistological analysis in 4 and 6 weeks. RESULTS: The CATT group suppressed joint instability in the ACL-T group (6 weeks; P = 0.032), and the CATR group suppressed joint instability in the DMM group (6 weeks; P = 0.032). Chondrocyte hypertrophy in the ACL-T and DMM groups was increased compared to the Sham group (6 weeks; [ACL-T vs Sham], P = 0.002, 95%CI [5.983-33.025]; [DMM vs Sham], P = 0.022, 95%CI [1.691-28.733]). In the subchondral bone, the BV/TV in the DMM and CATR groups was increased compared to the ACL-T and CATT groups (6 weeks; [DMM vs ACL-T], P = 0.002, 95%CI [7.404-37.582]; [DMM vs CATT], P = 0.014, 95%CI [2.881-33.059]; [CATR vs ACL-T], P = 0.006, 95%CI [4.615-34.793]; [CATR vs CATT], P = 0.048, 95%CI [0.092-30.270]). CONCLUSIONS: This study showed that joint instability promotes chondrocyte hypertrophy, but subchondral bone changes were influenced by differences in ACL and meniscus function.

Controlling joint instability after anterior cruciate ligament transection inhibits transforming growth factor-beta-mediated osteophyte formation.

OBJECTIVE: Abnormal joint instability contributes to cartilage damage and osteophyte formation. We investigated whether controlling joint instability inhibited chronic synovial membrane inflammation and delayed osteophyte formation and examined the role of transforming growth factor-beta (TGF-ß) signaling in the associated mechanism. DESIGN: Rats (n = 94) underwent anterior cruciate ligament (ACL) transection. Anterior tibial instability was either controlled (CAM group) or allowed to continue (SHAM group). At 2, 4, and 8 weeks after surgery, radiologic, histopathologic, immunohistochemical, immunofluorescent, and enzyme-linked immunosorbent assay examinations were performed to evaluate osteophyte formation and TGF-ß signaling. RESULTS: Joint instability increased cartilage degeneration score and osteophyte formation, and cell hyperplasia and proliferation and synovial thickening were observed in the synovial membrane. Major findings were increased TGF-ß expression and Smad2/3 following TGF-ß phosphorylation in synovial membarene, articular cartilage, and the posterior tibial growth plate (TGF-ß expression using ELISA: 4 weeks; P = 0.009, 95% CI [260.1-1340.0]) (p-Smad2/3 expression density: 4 weeks; P = 0.024, 95% CI [1.67-18.27], 8 weeks; P = 0.034, 95% CI [1.25-25.34]). However, bone morphogenetic protein (BMP)-2 and Smad1/5/8 levels were not difference between the SHAM model and the CAM model. CONCLUSIONS: This study showed that the difference between anterior tibial instability caused a change in the expression level of TGF in the posterior tibia and synovial membrane, and the reaction might be consequently involved in osteophyte formation.

A gene encoding a transmembrane protein is mutated in patients with diabetes mellitus and optic atrophy (Wolfram syndrome).

Wolfram syndrome (WFS; OMIM 222300) is an autosomal recessive neurodegenerative disorder defined by young-onset non-immune insulin-dependent diabetes mellitus and progressive optic atrophy. Linkage to markers on chromosome 4p was confirmed in five families. On the basis of meiotic recombinants and disease-associated haplotypes, the WFS gene was localized to a BAC/P1 contig of less than 250 kb. Mutations in a novel gene (WFS1) encoding a putative transmembrane protein were found in all affected individuals in six WFS families, and these mutations were associated with the disease phenotype. WFS1 appears to function in survival of islet beta-cells and neurons.

The effects of vanilloid analogues structurally related to capsaicin on the transient receptor potential vanilloid 1 channel.

Transient receptor potential vanilloid 1 (TRPV1) is known as a receptor of capsaicin, a spicy ingredient of chili peppers. It is also sensitive to a variety of pungent compounds and is involved in nociception. Here, we focused on the structural characteristics of capsaicin, and investigated whether vanillylmanderic acid (VMA), vanillic acid (VAcid), vanillyl alcohol (VAlc), vanillyl butyl ether (VBE), and vanillin, containing a vanillyl skeleton similar to capsaicin, affected the TRPV1 activities. For detection of TRPV1 activity, intracellular Ca2+ concentration ([Ca2+]i) was measured in HEK 293 cells heterologously expressing mouse TRPV1 (mTRPV1-HEK) and in mouse sensory neurons. Except for vanillin, four vanilloid analogues dose-dependently increased [Ca2+]i in mTRPV1-HEK. The solutions that dissolved VMA, VAcid and vanillin at high concentrations were acidic, whereas those of VAlc and VBE were neutral. Neutralized VAcid evoked [Ca2+]i increases but neutralized VMA did not. Mutation of capsaicin-sensing sites diminished [Ca2+]i responses to VAcid, VAlc and VBE. VAcid, VMA, and vanillin suppressed the activation of TRPV1 induced by capsaicin. VAcid and VMA also inhibited the acid-induced TRPV1 activation. In sensory neurons, VMA diminished TRPV1 activation by capsaicin or acids. The present data indicate that these structural characteristics of chemical compounds on TRPV1 may provide strategies for the development of novel analgesic drugs targeting nociceptive TRPV1.

A single-stranded DNA-cross-reactive immunogenic epitope of human homocysteine-inducible endoplasmic reticulum protein.

The mechanism involved in generating anti-DNA antibodies (Abs) remains unclear, as DNA is poorly immunogenic. Molecular mimicry between DNA and non-DNA substances has been implicated as a possible mechanism. We previously reported that homocysteine-inducible endoplasmic reticulum protein (Herp), which is induced by endoplasmic reticulum stress, is recognized by anti-double-stranded DNA (dsDNA) IgG from patients with systemic lupus erythematosus and that immunization with Herp elicits anti-dsDNA Abs in BALB/c mice. In this study, we observed that anti-single-stranded DNA (ssDNA) Abs were also generated in Herp-immunized BALB/c mice and established an anti-Herp monoclonal antibody (mAb), HT4, which specifically cross-reacted with ssDNA. The epitope of the HT4 mAb on Herp, 'EPAGSNR', was identified by screening a synthetic peptide library. The binding of the HT4 mAb to the peptide was competitively inhibited by ssDNA. Immunization of the epitope peptide elicited anti-ssDNA Abs in BALB/c mice. These results indicate that the epitope exists in a human self-protein, mimics ssDNA and shows antigenicity for anti-ssDNA Abs in normal mice. Anti-ssDNA Abs are often found in patients with drug-induced lupus erythematosus. Treatment with representative drugs that cause drug-induced lupus (chlorpromazine, procainamide and hydralazine) induced Herp expression and apoptosis in HeLa cells. These findings suggest that molecular mimicry between Herp and ssDNA is involved in anti-ssDNA Ab production in drug-induced lupus.

Selective use of the VHQ52 family in functional VH to DJH rearrangements in a B precursor cell line.

AT11-2, an Abelson virus-transformed cell line has DJH complexes on both chromosomes and is able to form functional variable region genes by the joins of VH genes to the DJH complexes during culture. Therefore we examined which VH gene family was used in functional VH to DJH recombinations in AT11-2. Surprisingly, of 32 independent functional VH to DJH recombinational events in AT11-2, 31 events used the VH segments of the VHQ52 family, and the remaining one used the VH segment of the VH7183 family. Thus, we describe here the first B precursor cell line that almost selectively uses the VHQ52 family in functional VH to DJH rearrangements. The selective use of the VHQ52 family in this B precursor cell line strongly indicates nonrandom use of VH gene families, and the existence of a stage at which the VHQ52 family is preferentially used during the normal development of early pre-B cells and has important implications for understanding the ontogeny of VH repertoire development. Furthermore, this cell line should prove extremely valuable in further studies of this kind.

Optimal positive airway pressure predicts oral appliance response to sleep apnoea.

Patients with less severe obstructive sleep apnoea (OSA) are usually prescribed oral appliances and/or smaller optimal nasal continuous positive airway pressure (P(nCPAP)) in nCPAP therapy. We hypothesised that OSA patients with greater P(nCPAP) would not respond favourably to oral appliances. Oral appliances were inserted in nCPAP users after washing-out the nCPAP effect. Follow-up polysomnography was undertaken with the adjusted oral appliance in place. The predictability of P(nCPAP) was evaluated with receiver-operating characteristic (ROC) curves. The median baseline apnoea/hypopnoea index (AHI) was reduced with the oral appliance from 36 to 12 events.h(-1) in 35 patients. When responders were defined as patients showing a follow-up AHI of <5 events.h(-1) with >50% reduction in baseline AHI, the area under the ROC curve for P(nCPAP) was 0.76. The best cut-off value of P(nCPAP) turned out to be 10.5 cmH(2)O with a high negative predictive value (0.93) and a low negative likelihood ratio (0.18). OSA patients with a P(nCPAP) of >10.5 cmH( 2)O are unlikely to respond to oral appliance therapy. This prediction is clinically helpful to both OSA patients and medical personnel in discussing oral appliances as a temporary substitute and/or alternative for nCPAP.

Observation of reversed-shear Alfvén eigenmodes excited by energetic ions in a helical plasma.

Reversed-shear Alfvén eigenmodes were observed for the first time in a helical plasma having negative q0'' (the curvature of the safety factor q at the zero shear layer). The frequency is swept downward and upward sequentially via the time variation in the maximum of q. The eigenmodes calculated by ideal MHD theory are consistent with the experimental data. The frequency sweeping is mainly determined by the effects of energetic ions and the bulk pressure gradient. Coupling of reversed-shear Alfvén eigenmodes with energetic ion driven geodesic acoustic modes generates a multitude of frequency-sweeping modes.

Functional and evolutionary insights into vertebrate kisspeptin systems from studies of fish brain.

The kiss1 gene product kisspeptin is now considered to be an essential regulator of the hypothalamic-pituitary-gonadal (HPG) axis in most vertebrate species. Recent findings in fishes are beginning to set a new stage for the kisspeptin study; the existence of paralogous kisspeptin genes as well as kisspeptin receptor (formerly called GPR54) genes has quite recently been reported in several fish and amphibian species. The fishes may provide excellent animal models for the study of general principles underlying the kisspeptin and kisspeptin receptor systems of vertebrates from the evolutionary viewpoint. Unlike placental and marsupial mammalian species mainly studied so far, many teleost species have two paralogous genes of kisspeptin, kiss1 and kiss2. Medaka, Oryzias latipes, in which kiss1 and kiss2 are expressed in distinctive hypothalamic neuron populations, is a good model system for the study of central regulation of reproduction. Here, the kiss1 system but not the kiss2 system shows expression dynamics strongly indicative of its direct involvement in the HPG axis regulation via its actions on GnRH1 neurons. On the other hand, the kiss1 gene is missing, and only kiss2 is expressed in some fish species. Also, there are some recent reports that Kiss2 peptide may be a potent regulator of reproduction in some fish species. The ancestral vertebrate probably already had two paralogous kiss genes, and their main function was the HPG axis regulation. In the species that retained both paralogues during evolution, either Kiss1 or Kiss2 predominantly retains its ability for the HPG axis regulation, while the other may assume new non-reproductive functions (neofunctionalization). Alternatively, both the paralogues may assume complementary functions in the HPG axis regulation (subfunctionalization). After the divergence of teleost and tetrapod lineages, either one of the two paralogues, or even both in birds, have been lost (degradation) or became a pseudogene (non-functionalization), but the remaining paralogue retained its original function of HPG axis regulation. The identification of multiple forms of kisspeptin receptors and the rather promiscuous ligand-receptor relationships has led to the further proposal that such promiscuousness may be the basis for the functional robustness of kisspeptin and kisspeptin receptor systems in the HPG axis regulation, when one or both paralogous genes are lost or functionally partitioned during evolution.

Increased insulin demand promotes while pioglitazone prevents pancreatic beta cell apoptosis in Wfs1 knockout mice.

AIMS/HYPOTHESIS: The WFS1 gene encodes an endoplasmic reticulum (ER) membrane-embedded protein called Wolfram syndrome 1 protein, homozygous mutations of which cause selective beta cell loss in humans. The function(s) of this protein and the mechanism by which the mutations of this gene cause beta cell death are still not fully understood. We hypothesised that increased insulin demand as a result of obesity/insulin resistance causes ER stress in pancreatic beta cells, thereby promoting beta cell death. METHODS: We studied the effect of breeding Wfs1 ( -/- ) mice on a C57BL/6J background with mild obesity and insulin resistance, by introducing the agouti lethal yellow mutation (A ( y ) /a). We also treated the mice with pioglitazone. RESULTS: Wfs1 ( -/- ) mice bred on a C57BL/6J background rarely develop overt diabetes by 24 weeks of age, showing only mild beta cell loss. However, Wfs1 ( -/- ) A ( y ) /a mice developed selective beta cell loss and severe insulin-deficient diabetes as early as 8 weeks. This beta cell loss was due to apoptosis. In Wfs1 ( +/+ ) A ( y ) /a islets, levels of ER chaperone immunoglobulin-binding protein (BiP)/78 kDa glucose-regulated protein (GRP78) and phosphorylation of eukaryotic translation initiation factor 2, subunit alpha (eIF2alpha) apparently increased. Levels of both were further increased in Wfs1 ( -/- ) A ( y ) /a murine islets. Electron micrography revealed markedly dilated ERs in Wfs1 (-/-) A ( y ) /a murine beta cells. Interestingly, pioglitazone treatment protected beta cells from apoptosis and almost completely prevented diabetes development. CONCLUSIONS/INTERPRETATION: Wfs1-deficient beta cells are susceptible to ER stress. Increased insulin demand prompts apoptosis in such cells in vivo. Pioglitazone, remarkably, suppresses this process and prevents diabetes. As common WFS1 gene variants have recently been shown to confer a risk of type 2 diabetes, our findings may be relevant to the gradual but progressive loss of beta cells in type 2 diabetes.

Epimorphin mediates mammary luminal morphogenesis through control of C/EBPbeta.

We have shown previously that epimorphin (EPM), a protein expressed on the surface of myoepithelial and fibroblast cells of the mammary gland, acts as a multifunctional morphogen of mammary epithelial cells. Here, we present the molecular mechanism by which EPM mediates luminal morphogenesis. Treatment of cells with EPM to induce lumen formation greatly increases the overall expression of transcription factor CCAAT/enhancer binding protein (C/EBP)beta and alters the relative expression of its two principal isoforms, LIP and LAP. These alterations were shown to be essential for the morphogenetic activities, since constitutive expression of LIP was sufficient to produce lumen formation, whereas constitutive expression of LAP blocked EPM-mediated luminal morphogenesis. Furthermore, in a transgenic mouse model in which EPM expression was expressed in an apolar fashion on the surface of mammary epithelial cells, we found increased expression of C/EBPbeta, increased relative expression of LIP to LAP, and enlarged ductal lumina. Together, our studies demonstrate a role for EPM in luminal morphogenesis through control of C/EBPbeta expression.

The ADRB3 Trp64Arg variant and BMI: a meta-analysis of 44 833 individuals.

BACKGROUND: The beta-3 adrenergic receptor gene (ADRB3) is part of the adrenergic system, which is known to play a key role in energy metabolism. The association between the Trp64Arg variant in the ADRB3 and body mass index (BMI) has been widely examined, but previous studies have been small and results have been inconsistent. METHODS: We assessed the association between the ADRB3 Trp64Arg variant and BMI in a large UK population-based cohort of 4854 middle-aged men and women. We also performed a meta-analysis of 97 studies, involving 44 833 individuals, to place our findings in context. RESULTS: Although we found no significant difference in BMI (0.20 kg/m(2), P=0.40) between the Trp64Trp homozygotes and Arg64 allele carriers in our UK population-based cohort, the meta-analysis showed significant association between the Arg64Trp variant and BMI, with Arg64-allele carriers having a 0.24 kg/m(2) (P=0.0002) higher BMI compared with noncarriers. However, we also found substantial heterogeneity among the studies (P=2.2 x 10(-14)). The difference in East Asians (0.31 kg/m(2), P=0.001) was 3.9 times larger than that in Europeans in whom no significant association was observed (0.08 kg/m(2), P=0.36). This was consistent with the chronological cumulative decrease in the effect size, which decreased steadily in Europeans and reached nonsignificance after 11 studies in 1996. In East Asians, the cumulative effect size decreased after the first reports, but reached a steady state at a significant effect size of 0.24 kg/m(2) in 2000. Although the funnel plot indicated no apparent publication bias, smaller studies tended to report greater differences in BMI, compared with larger studies. CONCLUSIONS: Collectively, these data suggest that the Trp64Arg ADRB3 genetic variant might be associated with BMI in East Asians, but not Europeans. More generally, our study shows the importance of meta-analyses in the field of genetic association studies for common traits. Each genetic variant makes only a small contribution to variation in BMI, and large sample sizes are needed to reliably assess and interpret gene-phenotype associations.

The Wilms' tumor gene WT1-GFP knock-in mouse reveals the dynamic regulation of WT1 expression in normal and leukemic hematopoiesis.

The Wilms' tumor gene WT1 is overexpressed in most of human leukemias regardless of disease subtypes. To characterize the expression pattern of WT1 during normal and neoplastic hematopoiesis, we generated a knock-in reporter green fluorescent protein (GFP) mouse (WT1(GFP/+)) and assayed for WT1 expression in normal and leukemic hematopoietic cells. In normal hematopoietic cells, WT1 was expressed in none of the long-term (LT) hematopoietic stem cells (HSC) and very few (<1%) of the multipotent progenitor cells. In contrast, in murine leukemias induced by acute myeloid leukemia 1 (AML1)/ETO+TEL/PDGFbetaR or BCR/ABL, WT1 was expressed in 40.5 or 38.9% of immature c-kit(+)lin(-)Sca-1(+) (KLS) cells, which contained a subset, but not all, of transplantable leukemic stem cells (LSCs). WT1 expression was minimal in normal fetal liver HSCs and mobilized HSCs, both of which are stimulated for proliferation. In addition, overexpression of WT1 in HSCs did not result in proliferation or expansion of HSCs and their progeny in vivo. Thus, the mechanism by which expansion of WT1-expressing cells occurs in leukemia remains unclear. Nevertheless, our results demonstrate that the WT1(GFP/+) mouse is a powerful tool for analyzing WT1-expressing cells, and they highlight the potential of WT1, as a specific therapeutic target that is expressed in LSCs but not in normal HSCs.

Optical measurement of Cs distribution in the large negative ion source.

To investigate a Cs behavior, optical diagnostic tools have been installed in the large negative ion source, an arc discharge used at large helical device neutral beam injector. A large Cs sputtering is observed during beam extraction due to the backstreaming H(+) ions. Distribution of Cs(+) light is uniform in the case of a balanced arc discharge, but large increase of Cs(+) light during beam extraction is observed in a nonuniform arc discharge. Controlling of the discharge uniformity is effective to reduce the local heat loading from the backstreaming H(+) ions at the backplate of ion source.

Neutral beam injection with an improved accelerator for LHD.

The beam profiles, port-through, rates and injection powers obtained with an improved accelerator with the multislot grounded grid are described. The accelerator has a combination of a steering grid with racetrack shaped aperture and multislot grounded grid to improve the beam optics. The optimal beam optics is obtained at the voltage ratio of 16.5-16.8, and the profiles are well fit by superposing multibeamlets with the divergent angles of 5.0 and 7.2 mrad along the direction parallel to the long and short axes of the slots of grounded grid. By adopting the racetrack shaped steering grid, the port-through rate increases from 34% to 38%, and the maximum injection power reaches 6 MW/187 keV.

Spectroscopic observations of beam and source plasma light and testing Cs-deposition monitor in the large area negative ion source for LHD-NBI.

In the large area negative ion source for the LHD negative-ion-(H(-))-based neutral beam system, (I) we used the spectrometer to measure caesium lines in the source plasma during beam shots. (II) With Doppler-shifted measurements, the H(alpha) line at three different locations along the beam as well as the spectrum profile for cases of different plasma grid areas. (III) Caesium deposition monitor with a high speed shutter was tested to measure the weight of the deposited Cs layer. In the observation, cleaner spectra of Doppler-shifted H(alpha) line with only a small level of background light were obtained at a new observation port which viewed the blueshifted light in the drift region after the accelerator of a LHD ion source. Both the amounts of Cs I (852 nm, neutral Cs(0)) and Cs II (522 nm, Cs(+)) in the source plasma light rose sharply when beam acceleration began, and continued rising during a 10 s pulse. It was thought that this was because the cesium was evaporated/sputtered from the source back plate by the back-streaming positive ions. Cs deposition rate to the crystal sensor measured by adjusting the shutter open time was evaluated to be 2.9 nanograms/s cm(2) for preliminary testing. More neutral Cs tended to be evolved in the source after arc discharge. Much Cs could be consumed in a high rate-pulsed operation (such as LHD source).

Antiapoptotic function of 17AA(+)WT1 (Wilms' tumor gene) isoforms on the intrinsic apoptosis pathway.

The WT1 gene is overexpressed in human primary leukemia and a wide variety of solid cancers. The WT1 gene is alternatively spliced at two sites, yielding four isoforms: 17AA(+)KTS(+), 17AA(+)KTS(-), 17AA(-)KTS(+), and 17AA(-)KTS(-). Here, we showed that 17AA(+)WT1-specific siRNA induced apoptosis in three WT1-expressing leukemia cell lines (K562, HL-60, and Kasumi-1), but not in WT1-non-expressing lymphoma cell line (Daudi). 17AA(+)WT1-specific siRNA activated caspase-3 and -9 in the intrinsic apoptosis pathway but not caspase-8 in the extrinsic one. On the other hand, 17AA(-)WT1-specific siRNA did not induce apoptosis in the three WT1-expressing cell lines. The apoptosis was associated with activation of proapoptotic Bax, which was activated upstream of the mitochondria. Constitutive expression of 17AA(+)WT1 isoforms inhibited apoptosis of K562 leukemia cells induced by apoptosis-inducing agents, etoposide and doxorubicin, through the protection of mitochondrial membrane damages, and DNA-binding zinc-finger region of 17AA(+)WT1 isoform was essential for the antiapoptotic functions. We further studied the gene(s) whose expression was altered by the expression of 17AA(+)WT1 isoforms and showed that the expression of proapoptotic Bak was decreased by the expression of 17AA(+)KTS(-)WT1 isoform. Taken together, these results indicated that 17AA(+)WT1 isoforms played antiapoptotic roles at some points upstream of the mitochondria in the intrinsic apoptosis pathway.

Human plasma epidermal growth factor/beta-urogastrone is associated with blood platelets.

Human epidermal growth factor (hEGF) has previously been isolated from urine and probably is identical to human beta-urogastrone (hUG). Immunoreactive hEGF/UG has been found in the plasma of normal subjects. In this study, using immunoaffinity chromatography to extract hEGF/UG from plasma, we found that immunoreactive hEGF/UG in blood was associated with blood platelets. It was present in platelet-rich, but not platelet-poor plasma and serum, and was found predominantly in the platelet fraction of whole blood. Sephadex G-50 Fine gel-exclusion chromatography of an extract of outdated blood bank platelets revealed two hEGF/UG components, one of which eluted in the void volume, and the other of which coeluted with purified standard hEGF/UG. The former hEGF/UG component was a high-molecular weight form that was cleaved into hEGF/UG by incubation with either mouse EGF/UG-associated arginine esterase or trypsin. It appeared to be identical to the high-molecular weight hEGF/UG previously reported in human urine, except for its apparently equal activities in radioimmunoassay and radioreceptor assay. The latter hEGF/UG component was immunologically, biologically, and physiochemically indistinguishable from highly purified hEGF/UG from human urine and was immunologically different from purified human platelet-derived growth factor. Platelet-associated hEGF/UG may account for the mitogenic activity of serum in cell lines in which platelet-derived growth factor is not active. Since hEGF/UG appears to be liberated from platelets during coagulation, platelet-associated EGF/UG may be involved in normal vascular and tissue repair and in the pathogenesis of atherosclerotic lesions. The discovery that the EGF/UG in plasma is associated with blood platelets raises important new possibilities for its role in human health and disease.

Interleukin-6 is a candidate molecule that transmits inflammatory information to the CNS.

Peripheral inflammation induces reactions within the CNS such as central sensitization, which is involved in the mechanism of inflammatory hyperalgesia. However, the precise mechanism of inflammatory signal transmission from the peripheral inflammatory site to the CNS is not clear. We studied the role of circulating interleukin (IL)-6 as a messenger of inflammatory information from the periphery to the CNS. In the rat model of inflammatory hyperalgesia induced by carrageenan, levels of IL-6 but not IL-1beta or tumor necrosis factor alpha (TNFalpha) were significantly elevated in the circulating blood 3 h after an injection of carrageenan. In addition, injecting carrageenan into the hind paw evoked thermal hyperalgesia and the release of prostaglandin E(2) (PGE(2)) from isolated blood vessels of the CNS ex vivo, as well as the induction of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES)-1 and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) in vascular endothelial cells of the CNS. A prior i.p. injection of IL-6 antiserum (IL-6AS) abolished or attenuated these responses. The present results suggested that circulating IL-6 could act as a messenger of inflammatory information from peripheral inflammatory sites to the CNS and as the afferent circulating signal to the CNS to produce prostaglandins in the vascular endothelial cells of the CNS through a COX-2 dependent pathway.