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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sickle-cell adherence to endothelium has been hypothesized to initiate or contribute to microvascular occlusion and pain episodes. Adherence involves plasma proteins, endothelial-cell adhesion molecules, and receptors on sickle erythrocytes. It has previously been reported that sickle reticulocytes express the alpha 4 beta 1 integrin receptor and bind to cytokine-activated endothelium via an alpha 4 beta 1/vascular-cell adhesion molecule-1 (VCAM-1) interaction. To elucidate other roles for alpha 4 beta 1 in sickle-cell adherence, the ability of activated alpha 4 beta 1 to promote adhesion to endothelium via a ligand different than VCAM-1 was explored. Adherence assays were performed under dynamic conditions at a shear stress of 1 dyne/cm2. Preincubation of sickle erythrocytes with phorbol 12,13-dibutyrate (PDBu) increased adherence of sickle cells eightfold as compared with untreated sickle cells. Normal erythrocytes, whether treated with PDBu or not, did not adhere to the endothelium. Activating anti-beta 1 antibodies 4B4 and 8A2 also increased the adhesion of sickle, but not normal, red blood cell (RBC) adhesion to endothelium. Anti-alpha 4 antibodies HP1/2 and HP2/1, inhibitory antibody 4B5, or an RGD peptide inhibited sickle-cell adherence induced by PDBu. Additional studies were undertaken to examine if fibronectin, a ligand for activated alpha 4 beta 1, was involved in PDBu-induced sickle erythrocyte adherence. Adherence of PDBu-treated sickle cells was completely inhibited by the CS-1 peptide of fibronectin. Fibronectin was detected on the surface of washed endothelium using an antifibronectin antibody in enzyme-linked immunosorbent assays. Antifibronectin antibody pretreatment of endothelial cells inhibited PDBu-induced adherence by 79% +/- 17%. Incubation of sickle RBCs with exogenous fibronectin after PDBu treatment inhibited adherence 86% +/- 8%. Taken together, these data suggest that endothelial-bound fibronectin mediates adherence of PDBu-treated sickle cells. Interleukin-8 (IL-8), a chemokine released in response to bacterial infection, viral infection, or other injurious agents, and known to activate integrins, also increased adherence of sickle erythrocytes to endothelial cells via fibronectin. This novel adherence pathway involving sickle-cell alpha 4 beta 1 activated by PDBu or IL-8 may therefore be relevant in vivo at vascular sites that produce IL-8 or similar agonists in response to vascular injury or immune activation. These observations describe ways in which inflammation and immune responses cause vasoocclusive complications in sickle-cell disease.
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PMID:Phorbol ester stimulation increases sickle erythrocyte adherence to endothelium: a novel pathway involving alpha 4 beta 1 integrin receptors on sickle reticulocytes and fibronectin. 894 72

Human immunodeficiency virus-1 (HIV-1) infection is associated with numerous effects on the nervous system, including pain and peripheral neuropathies. We now demonstrate that cultured rat dorsal root ganglion (DRG) neurons express a wide variety of chemokine receptors, including those that are thought to act as receptors for the HIV-1 coat protein glycoprotein120 (gp120). Chemokines that activate all of the known chemokine receptors increased [Ca(2+)](i) in subsets of cultured DRG cells. Many neurons responded to multiple chemokines and also to bradykinin, ATP, and capsaicin. Immunohistochemical studies demonstrated the expression of the CXCR4 and CCR4 chemokine receptors on populations of DRG neurons that also expressed substance P and the VR1 vanilloid receptor. RT-PCR analysis confirmed the expression of CXCR4, CX3CR1, CCR4, and CCR5 mRNAs in DRG neurons. Chemokines and gp120 produced excitatory effects on DRG neurons and also stimulated the release of substance P. Chemokines and gp120 also produced allodynia after injection into the rat paw. Thus these results provide evidence that chemokines and gp120 may produce painful effects via direct actions on chemokine receptors expressed by nociceptive neurons. Chemokine receptor antagonists may be important therapeutic interventions in the pain that is associated with HIV-1 infection and inflammation.
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PMID:Chemokines and glycoprotein120 produce pain hypersensitivity by directly exciting primary nociceptive neurons. 1143 78

The chemokines use G protein-coupled receptors to regulate the migratory and proadhesive responses of leukocytes. Based on observations that G protein-coupled receptors undergo heterologous desensitization, we have examined the ability of chemokines to also influence the perception of pain by cross-desensitizing opioid G protein-coupled receptors function in vitro and in vivo. We find that the chemotactic activities of both mu- and delta-opioid receptors are desensitized following activation of the chemokine receptors CCR5, CCR2, CCR7, and CXCR4 but not of the CXCR1 or CXCR2 receptors. Furthermore, we also find that pretreatment with RANTES/CCL5, the ligand for CCR1, and CCR5 or SDF-1alpha/CXCL12, the ligand for CXCR4, followed by opioid administration into the periaqueductal gray matter of the brain results in an increased rat tail flick response to a painful stimulus. Because chemokine administration into the periaqueductal gray matter inhibits opioid-induced analgesia, we propose that the activation of proinflammatory chemokine receptors down-regulates the analgesic functions of opioid receptors, and this enhances the perception of pain at inflammatory sites.
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PMID:Heterologous desensitization of opioid receptors by chemokines inhibits chemotaxis and enhances the perception of pain. 1213 Jun 63

Rheumatoid arthritis (RA) is a systemic, inflammatory autoimmune disorder that presents as a symmetric polyarthritis associated with swelling and pain in multiple joints, often initially occurring in the joints of the hands and feet. Articular inflammation causes activation and proliferation of the synovial lining, expression of inflammatory cytokines, chemokine-mediated recruitment of additional inflammatory cells, as well as B cell activation with autoantibody production. A vicious cycle of altered cytokine and signal transduction pathways and inhibition of programmed cell death contribute to synoviocyte and osteoclast mediated cartilage and bone destruction. A combination of targeted interventions at various stages in the pathogenesis of RA will likely be required to control symptoms in certain patients with this complex and potentially disabling disease. The regulation of rheumatoid synovial inflammation will be reviewed, followed by a brief summary of the therapeutic implications of these advances, including strategies targeting key cytokines, signal transduction molecules, co-stimulatory molecules, B cells, chemokines, and adhesion molecules.
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PMID:Rheumatoid arthritis: regulation of synovial inflammation. 1468 14

Chemokines are a family of peptides originally identified as the factors regulating the migration of leukocytes in inflammatory and immune responses. Recently, they have been shown to be produced in the central and peripheral nervous systems under various pathological conditions and act on neuronal and glial cells. In this study, we examined the production of monocyte chemoattractant protein-1 (MCP-1), a well-characterized chemokine, in dorsal root ganglia (DRG) in a rat model of neuropathic pain. Partial ligation of the sciatic nerve induced mechanical allodynia in the ipsilateral hindpaw with weaker allodynia in the contralateral one. Immunohistochemical analyses revealed that the number of MCP-1 immunoreactivity (ir)-positive cells was increased in the ipsilateral DRG. The increase started by 4h after the ligation, peaked at 24h and continued to at least 48 h. The weaker but significant increase was observed in the contralateral DRG. Double immunofluorescent staining demonstrated that almost all of the MCP-1ir-positive cells were neuronal cells. In situ hybridization histochemistry showed that MCP-1 mRNA expression was markedly upregulated in the ipsilateral DRG with weaker increase in the contralateral one at 24 h after the ligation, indicating that the elevation in MCP-1ir detected by immunohistochemistry was due to an upregulation of MCP-1 production by the DRG neurons themselves. Furthermore, intrathecal administration of MCP-1 induced mechanical allodynia. These results suggest that MCP-1 produced in the DRG neurons is involved in the development of mechanical allodynia induced by nerve injury.
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PMID:Enhanced production of monocyte chemoattractant protein-1 in the dorsal root ganglia in a rat model of neuropathic pain: possible involvement in the development of neuropathic pain. 1504 Dec

The N-methyl-d-aspartate receptor (NMDAR) has been strongly implicated in mechanisms of persistent pain states. The purpose of the present study was to determine whether the NMDAR NR-1, a key subunit in regulation of NMDAR channel complex is directly contributing to the onset and propagation of peripheral nerve injury-induced allodynia and whether N-methyl-d-aspartate (NMDA) signaling interacts with spinal chemokine (chemotactic cytokines) expression and glial activation. We used genetically engineered male mice that had their normal NR1 gene knocked out and expressed a modified NR1 gene at either normal level (NR1 +/+, wild type) or at a low level (NR1+/-, knock down). Each mouse underwent a peripheral nerve injury in which the lumbar 5 spinal segment (L5) nerve was transected. Mechanical allodynia was assessed using 0.008 and 0.015 g von Frey filaments on days 1, 3, 5, 7, 10, 14, 17 and 21 post-surgery. Mice were killed on day 21 and the harvested L5 spinal cord was analyzed for chemokine expression using RNAse protection assay. In a separate study, glial expression using immunohistochemistry was assessed in both groups 7 days following peripheral nerve injury. The NR1+/- mice displayed decreased mechanical allodynia in comparison to their wild type counterparts. However, even with dramatically impaired NMDA receptor signaling, there was still evidence of tactile hypersensitivity. Using the RPA analysis, we found decreases in mRNA chemokine expression in the NR1+/- mice as compared with NR1+/+ mice. There were no apparent differences in microglial or astrocytic expression between the wild type and knock down mice. These data provide important insights into the cascade of events involving the dynamic interaction between NMDAR function and spinal chemokine and glial production in neuropathic pain states. The results support the findings that chemokine signaling releases glutamate in the spinal cord.
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PMID:The role of the N-methyl-D-aspartate receptor NR1 subunit in peripheral nerve injury-induced mechanical allodynia, glial activation and chemokine expression in the mouse. 1505 Nov 65

Chronic Immune Dysschwannian/Dysneuronal Polyneuropathy is an autoimmune peripheral-nerve and/or nerve-root disorder known to usually respond to intravenous immunoglobulin-G treatment. Benefit can involve any combination of motor-nerve fibers and large and small sensory-nerve fibers responsible for a progressively crippling, unbalancing, discomforting or painful disorder. "Diabetic neuropathy" is commonly considered untreatable. However, 81% of my 48 recently-summarized type-2 diabetes patients with polyneuropathy, adequately-treated with intravenous immunoglobulin-G, off-label, were relieved, sometimes completely, of various motor and sensory symptoms, including pain, thereby resembling Chronic Immune Dysschwannian/Dysneuronal Polyneuropathy. Spinal fluid protein in them is often elevated, higher values seeming to auger a better intravenous immunoglobulin-G response. Continuing the improvement requires continuing the intravenous immunoglobulin-G treatment, indicating both intravenous immunoglobulin-G responsiveness and dependency. The intravenous immunoglobulin-G responsive type-2 diabetes polyneuropathy usually is dysschwannian, sometimes mainly dysneuronal intravenous immunoglobulin-G, the most beneficial and safest treatment, is costly, but if intravenous immunoglobulin-G-treatability of a dysimmune component of type-2 diabetes neuropathy is overlooked, dismissed or rejected, as commonly happens, other costs are high regarding the patient's worsening morbidity and disability, and resultant need for increased medical care. A novel intravenous immunoglobulin-G regimen effective for fragile patients is Two Non-Consecutive-Days Every Week, using 0.4 gm/kg body wt/day. Possible molecular mechanisms of intravenous immunoglobulin-G benefit are discussed. I propose that a) there is a higher incidence of Chronic Immune Dysschwannian/Dysneuronal Polyneuropathy-like neuropathy in type-2 diabetes patients and in patients with a strong family history of type-2 diabetes, and b) the intravenous immunoglobulin-G-treatable neuropathy in type-2 diabetes can be brought on by the genetico-diabetoid-2 state. The genetic-metabolic milieu (but not necessarily glucose dysmetabolism per se.) of type-2 diabetes putatively predisposes to the presumably-dysimmune intravenous immunoglobulin-G-responsive polyneuropathy. In some of our patients, especially ones having a strong type-2 diabetes genetic background, the intravenous immunoglobulin-G-responsive neuropathy preceded the diagnosis of type-2 diabetes by 5-10 years. Accordingly, Chronic Immune Dysschwannian/Dysneuronal Polyneuropathy patients having a strong type-2 diabetes genetic background are designated "genetico-diabetoid-2 neuropathy" prior to their manifesting type-2 diabetes. Intravenous immunoglobulin-G is herein suggested as a treatment for Severe Acute Respiratory Syndrome, a recent, and feared-repetitive, pandemic with many fatalities caused by a highly-contagious mutant coronavirus, for which there is no definitive treatment. Intravenous immunoglobulin-G might: a) combat a dysimmune component of Severe Acute Respiratory Syndrome, including the reactive cytokine-chemokine storm against respiratory tissues; b) contain some antibodies effective against the coronavirus non-specific components of Severe Acute Respiratory Syndrome; c) block host-cell receptors for the virus; and d) counteract secondary infections.
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PMID:Intravenous immunoglobulin G is remarkably beneficial in chronic immune dysschwannian/dysneuronal polyneuropathy, diabetes-2 neuropathy, and potentially in severe acute respiratory syndrome. 1508 99

Endogenous inhibition of inflammatory pain is mediated by leukocytes that secrete opioid peptides upon exposure to stress (cold water swim stress, CWS) or after local injection of corticotropin releasing factor (CRF). Since in early inflammation few opioid-containing leukocytes are detected and since peripheral opioid-mediated antinociception is low we examined whether antinociception could be augmented by increased recruitment of opioid-containing polymorphonuclear cells (PMN). Rats were intraplantarly (i.pl.) injected with Freund's complete adjuvant (FCA) and with the PMN-recruiting chemokine macrophage inflammatory protein-2 (MIP-2, 1-10 microg; control: saline) for 2 h. Intraplantar leukocytes were quantified by flow cytometry. Paw pressure threshold (PPT) was determined before and after exposure to CWS, i.pl. injection of CRF and opioid peptides. Opioid receptors (OR) were measured by binding studies in dorsal root ganglia (DRG) and by immunohistochemistry in the paw. Our studies showed that (i) MIP-2 injection dose-dependently augmented recruitment of PMN and opioid-containing leukocytes (5-fold increase in cells/paw, P < 0.05), (ii) PPT was not different between groups at baseline and after CWS or CRF (maximum MPE: 20+/-2.3-29+/-7.2%, P < 0.05), (iii) injection of opioid peptides dose-dependently increased the PPT (P < 0.05, maximum MPE: and 18+/-2.6-21+/-3.6%), (iv) MOR (micro OR, MOP) binding sites in the ipsilateral DRG were unchanged (24+/-2-22+/-1.2 fmol/mg protein, P < 0.05, ANOVA) and (v) the number of MOR and DOR (delta OR, DOP) stained nerve fibers in peripheral tissue were unaltered (both P > 0.05, t-test). In summary, antinociception during early inflammation is apparently not limited by the number of opioid-containing leukocytes but by OR availability.
Pain 2004 Mar
PMID:Endogenous peripheral antinociception in early inflammation is not limited by the number of opioid-containing leukocytes but by opioid receptor expression. 1510 9

Fractalkine is a unique chemokine reported to be constitutively expressed by neurons. Its only receptor, CX3CR1, is expressed by microglia. Little is known about the expression of fractalkine and CX3CR1 in spinal cord. Given that peripheral nerve inflammation and/or injury gives rise to neuropathic pain, and neuropathic pain may be partially mediated by spinal cord glial activation and consequent glial proinflammatory cytokine release, there must be a signal released by affected neurons that triggers the activation of glia. We sought to determine whether there is anatomical evidence implicating spinal fractalkine as such a neuron-to-glia signal. We mapped the regional and cellular localization of fractalkine and CX3CR1 in the rat spinal cord and dorsal root ganglion, under basal conditions and following induction of neuropathic pain, employing both an inflammatory (sciatic inflammatory neuropathy; SIN) as well as a traumatic (chronic constriction injury; CCI) model. Fractalkine immunoreactivity and mRNA were observed in neurons, but not glia, in the rat spinal cord and dorsal root ganglia, and levels did not change following either CCI or SIN. By contrast, CX3CR1 was expressed by microglia in the basal state, and the microglial cellular concentration was up-regulated in a regionally specific manner in response to neuropathy. CX3CR1-expressing cells were identified as microglia by their cellular morphology and positive OX-42 and CD4 immunostaining. The cellular distribution of fractalkine and CX3CR1 in the spinal circuit associated with nociceptive transmission supports a potential role in the mechanisms that contribute to the exaggerated pain state in these models of neuropathy.
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PMID:Fractalkine (CX3CL1) and fractalkine receptor (CX3CR1) distribution in spinal cord and dorsal root ganglia under basal and neuropathic pain conditions. 1534 87

Tachykinins represent a family of neuropeptides sharing similar C-terminus sequences, but exhibiting preferential binding to one of three receptors called neurokinin receptors (NK-R). While known for its role in contracting smooth muscle or acting as a pain signal neurotransmitter, substance P (SP) and other tachykinins can directly influence immune responses. Studies from the early 1980s revealed that human lymphocytes bore NK-R, but it remains unclear, even to-date, why such receptors are expressed on leukocytes. Nerve tracing studies have provided some speculation that the nervous system can assist the immune system in stimulating an immune response dependent upon which neuropeptide-bearing fibers infiltrate specific lymphoid structures. Such observations have important implications for regulating mucosal responses given that tachykinin-bearing nerve fibers extensively innervate the gut, and SP concentrations in the gut are second only to the brain. Such evidence suggests that SP and related neuropeptides may be important in controlling bacterial infections of the gut. This is shown by blocking SP action in which mice show increased susceptibility to Salmonella infections since induction of IFN-gamma is significantly reduced. In addition, the absence or its presence of SP's or the newly discovered lymphocyte-derived neurokinin called hemokinin's action can modify host IgA responses. Thus, tachykinins introduce new circuits to immune regulation suggesting that these neuropeptides exhibit cytokine- and chemokine-like action.
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PMID:The role of tachykinins on bacterial infections. 1535 50


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