CCL9/MIP-1gamma and its receptor CCR1 are the major chemokine ligand/receptor species expressed by osteoclasts

Although much has been learned recently of the mechanisms by which the differentiation of osteoclasts is induced, less is known of the factors that regulate their migration and localization, and their interactions with other bone cells. In related cell types, chemokines play a major role in these processes. We therefore systematically tested the expression of RNA for chemokines and their receptors by osteoclasts. Because bone is the natural substrate for osteoclasts and may influence osteoclast behavior, we also tested expression on bone slices. Quantitative RT-PCR using real-time analysis with SYBR Green was therefore performed on RNA isolated from bone marrow cells after incubation with macrophage-colony stimulating factor (M-CSF) with/without receptor-activator of NFkappaB ligand (RANKL), on plastic or bone. We found that RANKL induced expression of CCL9/MIP-1gamma to levels comparable to that of tartrate-resistant acid phosphatase (TRAP), a major specialized product of osteoclasts. CCL22/MDC, CXCL13/BLC/BCA-1, and CCL25/TECK were also induced. The dominant chemokine receptor expressed by osteoclasts was CCR1, followed by CCR3 and CX3CR1. Several receptors expressed on macrophages and associated with inflammatory responses, including CCR2 and CCR5, were down-regulated by RANKL. CCL9, which acts through CCR1, stimulated cytoplasmic motility and polarization in osteoclasts, identical to that previously observed in response to CCL3/MIP-1alpha, which also acts through CCR1 and is chemotactic for osteoclasts. These results identify CCL9 and its receptor CCR1 as the major chemokine and receptor species expressed by osteoclasts, and suggest a crucial role for CCL9 in the regulation of bone resorption.     

Conductance states activated by glycine and GABA in rat cultured spinal neurones

Summary The conductance properties of single Cl^– channels activated by glycine and gamma-aminobutyric acid (GABA) were examined in rat spinal cord neurones grown in cell culture. The majority (85%) of spinal neurones were sensitive to both glycine and GABA as were most (83%) outside-out patches tested. Glycine and GABA activated multiple conductance state Cl^– channels with linear current-voltage properties when the chloride activities of the solutions bathing both sides of the membrane were similar. Glycine activated six distinct conductance states with conductances of 14, 20, 30, 43, 64 and 93 pS, whereas GABA activated five states with conductances of 13, 20, 29, 39 and 71 pS. The 30 and 43 pS states and the 20 and 29 pS states were observed most frequently with glycine and GABA, respectively. As the values of the glycine- and GABA-activated conductance states form a geometric progression when arranged in ascending order, we concluded that the channels do not consist of a cluster of identical pores. Additional conductance states (50 and 100 pS) were activated by glycine occasionally. The similarity between the conductances of the states activated by the two transmitters is consistent with the proposal that they both activate the same type of Cl^– channel.     

神经激肽-1(NK-1)受体介导福尔马林诱发的大鼠脊髓c-fos表达

本文用Ｆｏｓ作为背角伤害性反应神经元活动的一个标志物,结合免疫细胞化学和神经药理学方法,观察了速激肽受体拮抗剂对福尔马林诱发的脊髓ｃ－ｆｏｓ原癌基因表达的影响。一侧大鼠后肢跖部皮下注射福尔马林,仅在同侧脊髓背角有ｃ－ｆｏｓ表达。Ｆｏｓ阳性神经元最密集分布于Ｉ层和Ⅱ层背侧的内侧部,中等量分布于Ⅳ层和Ｖ型,少量定位于Ⅱ层腹侧部、Ⅲ、Ⅵ和Ⅹ层。若预先在一侧大鼠后肢跖部皮下注射福尔马林前,鞘内给予神经激肽     

The chemokine interleukin-8 acutely reduces Ca(2+) currents in identified cholinergic septal neurons expressing CXCR1 and CXCR2 receptor mRNAs

The chemokine IL-8 is known to be synthesized by glial cells in the brain. It has traditionally been shown to have an important role in neuroinflammation but recent evidence indicates that it may also be involved in rapid signaling in neurons. We investigated how IL-8 participates in rapid neuronal signaling by using a combination of whole-cell recording and single-cell RT-PCR on dissociated rat septal neurons. We show that IL-8 can acutely reduce Ca(2+) currents in septal neurons, an effect that was concentration-dependent, involved the closure of L- and N-type Ca(2+) channels, and the activation of G(ialpha1) and/or G(ialpha2) subtype(s) of G-proteins. Analysis of the mRNAs from the recorded neurons revealed that the latter were all cholinergic in nature. Moreover, we found that all cholinergic neurons that responded to IL-8, expressed mRNAs for either one or both IL-8 receptors CXCR1 and CXCR2. This is the first report of a chemokine that modulates ion channels in neurons via G-proteins, and the first demonstration that mRNAs for CXCR1 are expressed in the brain. Our results suggest that IL-8 release by glial cells in vivo may activate CXCR1 and CXCR2 receptors on cholinergic septal neurons and acutely modulate their excitability by closing calcium channels.     

Altered chemokine expression in the spinal cord and brain contributes to differential interleukin-1beta-induced neutrophil recruitment

The pattern of neutrophil recruitment that accompanies inflammation in the CNS depends on the site of injury and the stage of development. The adult brain parenchyma is refractory to neutrophil recruitment and associated damage as compared to the spinal cord or juvenile brain. Using quantitative Taqman RT-PCR and enzyme-liked immunosorbent assay (ELISA), we compared mRNA and protein expression of the rat neutrophil chemoattractant chemokines (CINC) in spinal cord and brain of adult and juvenile rats to identify possible association with the observed differences in neutrophil recruitment. Interleukin-1beta (IL-1beta) injection resulted in up-regulated chemokine expression in both brain and spinal cord. CINC-3 mRNA was elevated above CINC-1 and CINC-2alpha, with expression levels for each higher in spinal cord than in brain. By ELISA, IL-1beta induced greater CINC-1 and CINC-2alpha expression compared to CINC-3, with higher protein levels in spinal cord than in brain. In the juvenile brain, significantly higher levels of CINC-2alpha protein were observed in response to IL-1beta injection than in the adult brain following an equivalent challenge. Correspondingly, neutrophil recruitment was observed in the juvenile brain and adult spinal cord, but not in the adult brain. No expression of CINC-2beta mRNA was detected. Thus differential chemokine induction may contribute to variations in neutrophil recruitment in during development and between the different CNS compartments.     

Embryonic rat spinal cord neurons change expression of glycine receptor subtypes during development in vitro

The expression of functional glycine receptors (GlyRs) by embryonic rat spinal cord neurons during development in vitro was investigated using whole-cell patch-clamp recordings. Functional GlyRs were expressed by most neurons within 1 day in vitro, and by all neurons from 4 days onward. However, the extent to which responses to glycine were blocked by the antagonist strychnine differed significantly between the first few days and 8 days in culture. Responses to glycine by neurons during the first few days in culture exhibited significantly less blockade by strychnine than those in neurons after 1 week in culture. Responses to glycine at both ages reflected an increased conductance to chloride ions, ruling out involvement of N-methyl-D -aspartate type glutamate receptors, and were not due to cross activation of γ-aminobutyric acid receptors. Monoclonal antibody 4a, which recognizes multiple subtypes of rat GlyR α subunits, labeled most neurons as early as 1 day in vitro, confirming that neurons express some form of GlyR α subunits by the first day in culture. These results show that rat spinal cord neurons express GlyRs early in their differentiation in vitro, and they suggest that individual neurons express as functional, cell-surface GlyRs a strychnine-insensitive isoform of the GlyR, possibly the previously described α2^* subunit. In addition, these results indicate that the expression of GlyR isoforms changes from predominantly a strychnine-insensitive isoform to other, strychnine-sensitive isoform(s) GlyR during development in vitro. © 1997 John Wiley & Sons, Inc. J Neurobiol 32: 579–592, 1997     

Induction of chemokines and chemokine receptors CCR2b and CCR4 in authentic human osteoclasts differentiated with RANKL and osteoclast like cells differentiated by MCP-1 and RANTES

Chemokines MCP-1 and RANTES are induced when authentic bone resorbing human osteoclasts differentiate from monocyte precursors in vitro. In addition, MCP-1 and RANTES can stimulate the differentiation of cells with the visual appearance of osteoclasts, being multinuclear and positive for tartrate resistance acid phosphatase (TRAP +). We show here that MIP1alpha is also potently induced by RANKL during human osteoclast differentiation and that this chemokine also induces the formation of TRAP + multinucleated cells in the absence of RANKL. MIP1alpha was able to overcome the potent inhibition of GM-CSF on osteoclast differentiation, permitting the cells to pass through to TRAP + multinuclear cells, however these were unable to form resorption pits. Chemokine receptors CCR2b and CCR4 were potently induced by RANKL (12.6- and 49-fold, P = 4.0 x 10(-7) and 4.0 x 10(-8), respectively), while CCR1 and CCR5 were not regulated. Chemokine treatment in the absence of RANKL also induced MCP-1, RANTES and MIP1alpha. Unexpectedly, treatment with MCP-1 in the absence of RANKL resulted in 458-fold induction of CCR4 (P = 1.0 x 10(-10)), while RANTES treatment resulted in twofold repression (P = 1.0 x 10(-4)). Since CCR2b and CCR4 are MCP-1 receptors, these data support the existence of an MCP-1 autocrine loop in human osteoclasts differentiated using RANKL.     

Glycine is taken up through GLYT1 and GLYT2 transporters into mouse spinal cord axon terminals and causes vesicular and carrier-mediated release of its proposed co-transmitter GABA

Glycine and GABA are likely co-transmitters in the spinal cord. Their possible interactions in presynaptic terminals have, however, not been investigated. We studied the effects of glycine on GABA release using superfused mouse spinal cord synaptosomes. Glycine concentration dependently elicited [(3)H]GABA release which was insensitive to strychnine or 5,7-dichlorokynurenic acid, but was Na(+) dependent and sensitive to the glycine uptake blocker glycyldodecylamide. The glycine effect was external Ca(2+) independent, but was reduced when intraterminal Ca(2+) was chelated with 1,2-bis-(2-aminophenoxy)ethane-N,N,N',N'-tetracetic acid or depleted with thapsigargin, or when vesicular storage was impaired with bafilomycin. Glycine-induced [(3)H]GABA release was prevented, in part, by blocking GABA transport. The glycine effect was halved by sarcosine, a GLYT1 substrate/inhibitor, or by amoxapine, a GLYT2 blocker, and abolished by a mixture of the two. The sensitivity to sarcosine, used as a transporter inhibitor or substrate, persisted in synaptosomes prelabelled with [(3)H]GABA in the presence of beta-alanine, excluding major gliasome involvement. To conclude, in mice spinal cord, transporters for glycine (both GLYT1 and GLYT2) and for GABA coexist on the same axon terminals. Activation of the glycine transporters elicits GABA release, partly by internal Ca(2+)-dependent exocytosis and partly by transporter reversal.     

Adult rat spinal cord culture on an organosilane surface in a novel serum-free medium

Summary In this study, we have documented by morphological analysis, immunocytochemistry, and electrophysiology, the development of a culture system that promotes the growth and long-term survival of dissociated adult rat spinal cord neurons. This system comprises a patternable, nonbiological, cell growth-promoting organosilane substrate coated on a glass surface and an empirically derived novel serum-free medium, supplemented with specific growth factors (acidic fibroblast growth factor, heparin sulfate, neurotrophin-3, brain-derived neurotrophic factor, glial-derived neurotrophic factor, cardiotrophin-1, and vitronectin). Neurons were characterized by immunoreactivity for neurofilament 150, neuron-specific enolase, Islet-1 antibodies, electrophysiology, and the cultures were maintained for 4–6 wk. This culture system could be a useful tool for the study of adult mammalian spinal neurons in a functional in vitro system.     

亚低温对脊髓损伤后反应性星形胶质细胞增生的影响

目的：观察在不同温度条件下脊髓星形胶质细胞划痕损伤活化后的形态和活性改变,以探讨亚低温对脊髓损伤后反应性星形胶质细胞增生的影响。方法：体外原代培养新生SD大鼠脊髓星形胶质细胞,以划痕实验制备反应性星形胶质细胞。亚低温选择33℃,细胞培养48 h。实验分为对照组、划痕组、亚低温组和划痕+亚低温组。各组在相应的时间点观察细胞形态,采用免疫荧光染色方法检测Nestin阳性率,MTT比色法观察细胞活性,PI染色方法观察细胞凋亡程度。结果：与对照组和亚低温组相比,划痕组和划痕+亚低温组细胞胞体肥大,周围突起增多、延展以及胞浆丰富,细胞生长率明显升高。与划痕组相比,划痕+亚低温组细胞变化减慢,周围突起减少,细胞长入划痕处所需时间增加,细胞Nestin阳性率、PI阳性率和细胞生长率明显降低,各结果差异显著（P<0.01）。结论：划痕损伤后星形胶质细胞活化为反应性星形胶质细胞并会增生,亚低温明显抑制脊髓反应性星形胶质细胞的活化增生,并可以抑制星形胶质细胞的凋亡。     

ERK 1/2 signaling pathway is involved in nicotine-mediated neuroprotection in spinal cord neurons

Evidence indicates that agonists of neuronal nicotinic receptors (nAChRs), including nicotine, can induce neuroprotective and anti-apoptotic effects in the CNS. To study these mechanisms, the present study focused on nicotine-mediated modulation of the extracellular regulated kinase 1 and 2 (ERK1/2) pathway in cultured spinal cord neurons. Exposure to nicotine (0.1-10 microM) for as short as 1 min markedly upregulated levels of phosphorylated ERK1/2 (pERK1/2) and increased total ERK1/2 activity. Inhibition studies with mecamylamine and alpha-bungarotoxin revealed that these effects were mediated by the alpha7 nicotinic receptor. In addition, pre-exposure to U0126, a specific inhibitor of the ERK1/2 signaling, prevented nicotine-mediated anti-apoptotic effects. To indicate if treatment with nicotine also can activate ERK1/2 in vivo, a moderate spinal cord injury (SCI) was induced in rats using a weight-drop device and nicotine was injected 2 h post-trauma. Consistent with in vitro data, nicotine increased levels of pERK1/2 in this animal model of spinal cord trauma. Results of the present study indicate that the ERK1/2 pathway is involved in anti-apoptotic effects of nicotine in spinal cord neurons and may be involved in therapeutic effects of nicotine in spinal cord trauma.     

The development of mouse spinal cord in tissue culture

Summary Whole mouse embryos were grown in vitro from Theiler stage 12 (1 to 7 somites) to Theiler stages 15 and 16 (25 to 35 somites). This procedure gives experimental access to precisely staged embryos during the early period of neurogenesis. To follow the further development of neurons in vitro, fragments of spinal primordia were set up from these cultured embryos. In such cultures, the proliferation of precursor cells, the formation of postmitotic cells and, finally, the cytodifferentiation of neurons were observed. A preliminary account of this work was given at the Tissue Culture Association Meeting in 1977, and the Canadian Federation of Biological Societies Meeting in 1977 (1,2). This work was supported by Grant MT 4235 from the Medical Research Council of Canada.     

Identification of CCR2-binding features in Cytl1 by a CCL2-like chemokine model

Chemokines are small secreted proteins that play an important role in immune responses and have also been shown to be involved in cartilage development and contributing to pathogenesis of a variety of diseases. They present a conserved 3D structure, so-called IL8-like chemokine fold, which is supported by conserved cysteines forming intra-molecular disulfide bonds. These cysteine sequence motifs have often been used to find new chemokine family members by sequence-based database searches. However, it has been shown that different patterns can provide disulfide bonds fitting into an IL8-like architecture, which has been the key to identify new remote homologues of the IL8-like chemokine family. We report a structural-functional characterization of cytokine-like protein 1 (Cytl1) by a combination of different computational structure-based techniques. Previous studies based on sequence analysis and secondary structure predictions reported that Cytl1 might adopt a 4-helical cytokine fold. However, our detailed molecular modeling studies and structure-based functional analysis strongly suggest that Cytl1 is more likely to adopt an IL8-like chemokine fold, in particular similar to CCL2 (monocyte chemoattractant protein 1, MCP-1). Moreover, we identify in a CCL2-like 3D model of Cytl1 the necessary reported features to signal through the chemokine receptor CCR2. Those discovered structural features of Cytl1 as CCL2-like chemokine, together with the fact that both, CCL2 and Cytl1, are known to be involved in cartilage development and pathogenesis of osteoarthritis and rheumatoid arthritis, make us hypothesize that Cytl1 could be a structurally and functionally related analog of CCL2 signaling through the chemokine receptor CCR2.     

Effects of selective COX-1 and -2 inhibition on formalin-evoked nociceptive behaviour and prostaglandin E(2) release in the spinal cord.

Nociception evoked prostaglandin (PG) release in the spinal cord considerably contributes to the induction of hyperalgesia and allodynia. To evaluate the relative contribution of cyclooxygenase-1 (COX-1) and COX-2 in this process we assessed the effects of the selective COX-1 inhibitor SC560 and the selective COX-2 inhibitor celecoxib on formalin-evoked nociceptive behaviour and spinal PGE(2) release. SC560 (10 and 20 mg/kg) significantly reduced the nociceptive response and completely abolished the formalin-evoked PGE(2) raise. In contrast, celecoxib (10 and 20 mg/kg) was ineffective in both regards, i.e. the flinching behaviour was largely unaltered and the formalin-induced PGE(2) raise as assessed using microdialysis was only slightly, not significantly reduced. This suggests that the formalin-evoked rapid PG release was primarily caused by COX-1 and was independent of COX-2. Mean free spinal cord concentrations of celecoxib during the formalin assay were 32.0 +/- 4.5 nM, thus considerably higher than the reported IC50 for COX-2 (3-7 nM). Therefore, the lack of efficacy of celecoxib is most likely not to be a result of poor tissue distribution. COX-2 mRNA and protein expression in the spinal cord were not affected by microdialysis alone but the mRNA rapidly increased following formalin injection and reached a maximum at 2 h. COX-2 protein was unaltered up to 4 h after formalin injection. The time course of COX-2 up-regulation suggests that the formalin-induced nociceptive response precedes COX-2 protein de novo synthesis and may therefore be unresponsive to COX-2 inhibition. Considering the results obtained with the formalin model it may be hypothesized that the efficacy of celecoxib in early injury evoked pain may be less than that of unselective NSAIDs.     

Irbesartan attenuates ischemic brain damage by inhibition of MCP-1/CCR2 signaling pathway beyond AT1 receptor blockade

Angiotensin II type 1 (AT₁) receptor blockers (ARBs) are known to prevent the onset of stroke and to attenuate neural damage. Additional beneficial effects of ARBs, independent of AT₁ receptor blockade, have been highlighted. Irbesartan is reported to act as an antagonist of the monocyte chemoattractant protein-1 (MCP-1) receptor, C–C chemokine receptor 2 (CCR2), due to its molecular structure. We examined the possible synergistic effects of co-administration of irbesartan with propagermanium, a CCR2 antagonist, on ischemic brain damage. Administration of propagermanium decreased ischemic brain area after middle cerebral artery occlusion (MCAO). To study the possible synergistic effects of propagermanium with ARBs, we employed non-effective lower doses of irbesartan and losartan. Administration of irbesartan with propagermanium decreased the ischemic brain area more markedly compared with propagermanium alone, but co-administration of losartan did not. MCP-1 mRNA level was significantly increased on the ipsilateral side after MCAO, and administration of irbesartan with propagermanium decreased the MCP-1 level, whereas co-administration of losartan did not. Similar results were obtained for MCP-1 protein level. CCR2 mRNA expression was significantly elevated on the ipsilateral side; however, no significant difference was observed between each group. mRNA levels of other inflammatory cytokines such as TNF-α and IL-1β also significantly increased on the ipsilateral side, but the expression levels were not changed by each drug treatment. Taking these findings together, irbesartan exerts more beneficial effects on ischemic brain damage with an MCP-1 receptor blocker, at least due to its inhibitory effects on MCP-1/CCR2 signaling beyond AT₁ receptor blockade.     

Cathepsin B mRNA and protein expression following contusion spinal cord injury in rats

We provide the first data that cathepsin B (Cath B), a lysosomal cysteine protease, is up-regulated following contusion-spinal cord injury (SCI). Following T12 laminectomy and moderate contusion, Cath B mRNA and protein expression profiles were examined from 2 to 168 h post-injury in rats using real-time PCR and immunoblots, respectively. Contusion injury significantly increased [mRNA]Cath B in the injury site and adjacent segments over sham injury levels. While the largest [mRNA]Cath B induction (20-fold over naive) was seen in the injury site, the caudal segment routinely yielded [mRNA]Cath B levels greater than 10-fold over naive. Interestingly, sham injury animals also experienced mRNA induction at several time points at the injury site and in segments rostral and caudal to the injury site. Contusion injury also significantly elevated levels of Cath B proenzyme protein (37 kDa) over sham injury in the injury site (48, 72 and 168 h post-injury). Furthermore, significant protein increases of single and double chain Cath B (both active forms) occurred at the injury site at 72 and 168 h post-injury. Similar significant increases in Cath B protein levels were seen in areas adjacent to the injury site. The induction of Cath B mRNA and protein expression following contusion injury is previously undescribed and suggests that Cath B may potentially be involved in the secondary injury cascade, perhaps for as long as 1 week post-injury.     

Proteolytic processing and inactivation of CCL2/MCP-1 by meprins

Monocyte chemotactic protein 1 (CCL2/MCP-1) is a small chemokine involved in the recruitment and trafficking of mononuclear immune cells to inflammation sites. Our studies demonstrate that the metalloendopeptidases meprin A (purified from kidney cortex), recombinant meprin α, and recombinant meprin β can all process CCL2/MCP-1. The cleavage sites were determined by amino acid sequencing and mass spectrometry analysis of the generated products, and the biological activity of the products was evaluated by chemotactic migration assay using THP-1 cells. The cleavage sites generated by the meprin isoforms revealed that meprin A and meprin α cleaved the N-terminal domain of mouse CCL2/MCP-1 at the Asn⁶ and Ala⁷ bond, resulting in significant reduction in the chemotactic activity of the cleaved CCL2/MCP-1. Meprin β was unable to cleave the N-terminus of mouse CCL2/MCP-1 but cleaved the C-terminal region between Ser⁷⁴ and Glu⁷⁵. Human CCL2/MCP-1 that lacks the murine C-terminal region was also cleaved by meprin α at the N-terminus resulting in significant loss of CCL2/MCP-1 biological activity, whereas meprin β did not affect the biological activity. These studies suggest that meprin α and meprin β may play important roles in regulating the CCL2/MCP-1 chemokine activity during inflammation.     

甲醛炎性痛对大鼠脊髓HO-1表达的影响

目的:观察足底注射甲醛引起的外周组织炎性疼痛是否可诱导大鼠脊髓血红素氧合酶-1(HO-1)表达发生改变以及变化的时程特征。方法:健康雄性SD大鼠随机分为7组(n=6):对照组(control组)、甲醛6 h组(F6 h组)、甲醛12 h(F12 h组)、甲醛1 d组(F1 d组)、甲醛2 d组(F2 d组)、甲醛3 d组(F3 d组)和甲醛7 d组(F7 d组)。采用足底注射甲醛溶液复制炎性痛模型,采用免疫组织化学方法检测左、右两侧脊髓后角以及中央管周围灰质HO-1蛋白的表达。结果:Control组大鼠HO-1免疫反应阳性细胞在脊髓后角及中央管周围灰质仅有少量分布,且这些细胞染色较浅。足底注射甲醛后6 h,L5节段双侧脊髓后角和中央管周围灰质HO-1免疫反应阳性细胞数目即有所增多,足底注射甲醛后12 h时,双侧脊髓后角和中央管周围灰质HO-1免疫反应阳性细胞数目进一步增多,阳性细胞染色明显加深,1 d时阳性细胞数目和染色深度均达到高峰,7 d时仍高于control组水平。各时间点双侧脊髓后角比较,阳性细胞数目和阳性细胞染色深度均无明显差异。结论:大鼠足底注射甲醛引起的炎性痛可诱导双侧脊髓后角和中央管周围灰质HO-1表达增多,以注射甲醛后1 d时增多最为明显。