myelin-basic-protein and Pain

Painful and disabling musculoskeletal disorders remain prevalent. In rats trained to perform repetitive tasks leading to signs and dysfunction similar to those in humans, we tested whether manual therapy would prevent the development of the pathologies and symptoms. We collected behavioral, electrophysiological, and histological data from control rats, rats that trained for 5 weeks before performing a high-repetition high-force (HRHF) task for 3 weeks untreated, and trained rats that performed the task for 3 weeks while being treated 3x/week using modeled manual therapy (MMT) to the forearm (HRHF + MMT). The MMT included bilateral mobilization, skin rolling, and long axis stretching of the entire upper limb. High-repetition high-force rats showed decreased performance of the operant HRHF task and increased discomfort-related behaviors, starting after training. HRHF + MMT rats showed improved task performance and decreased discomfort-related behaviors compared with untreated HRHF rats. Subsets of rats were assayed for presence or absence of ongoing activity in C neurons and slow Aδ neurons in their median nerves. Neurons from HRHF rats had a heightened proportion of ongoing activity and altered conduction velocities compared with control and MMT-treated rats. Median nerve branches in HRHF rats contained increased numbers of CD68 macrophages and degraded myelin basic protein, and showed increased extraneural collagen deposition, compared with the other groups. We conclude that the performance of the task for 3 weeks leads to increased ongoing activity in nociceptors, in parallel with behavioral and histological signs of neuritis and nerve injury, and that these pathophysiologies are largely prevented by MMT.

Topics: Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Case-Control Studies; Cumulative Trauma Disorders; Disease Models, Animal; Electrophysiology; Fasting; Female; Gait Disorders, Neurologic; Inflammation; Median Nerve; Musculoskeletal Manipulations; Myelin Basic Protein; Nociceptors; Pain; Rats; Rats, Sprague-Dawley; Statistics, Nonparametric

Neurotrauma frequently results in neuropathic pain. Our earlier studies revealed that peripheral neurotrauma-induced fragmentation of the myelin basic protein (MBP), a major component of the myelin sheath formed by Schwann cells, initiates a pain response from light touch stimuli (mechanical allodynia) in rodents. Here, we identified the cyclin-dependent kinase 5 (CDK5), as an intracellular interactor of MBP in Schwann cells. The algesic peptide fragment of MBP directly associated with CDK5. When complexed with its p25 coactivator, CDK5 phosphorylated the conserved MBP sequence. The expressed MBP fragment colocalized with CDK5 in Schwann cell protrusions. Roscovitine, an ATP-competitive CDK5 inhibitor, disrupted localization of the expressed MBP peptide. Mutations in the evolutionary conserved MBP algesic sequence resulted in the interference with intracellular trafficking of the MBP fragment and kinase activity of CDK5 and diminished pain-like behavior in rodents. Our findings show that MBP fragment amino acid sequence conservation determines its interactions, trafficking, and pronociceptive activity. Because CDK5 activity controls both neurogenesis and nociception, the algesic MBP fragment may be involved in the regulation of the CDK5 functionality in pain signaling and postinjury neurogenesis in vertebrates.. The novel RNA-seq datasets were deposited in the GEO database under the accession number GSE107020.

Topics: Amino Acid Sequence; Animals; Cells, Cultured; Conserved Sequence; Cyclin-Dependent Kinase 5; Female; Hyperalgesia; Myelin Basic Protein; Pain; Peptide Fragments; Phosphorylation; Rats; Rats, Sprague-Dawley; Schwann Cells; Sequence Homology; Signal Transduction

Although the contributions of microglia and astrocytes to chronic pain pathogenesis have been a focal point of investigation in recent years, the potential role of oligodendrocytes, another major type of glial cells in the CNS that generates myelin, remains largely unknown.. We report here that cell markers of the oligodendrocyte lineage, including NG2, PDGFRa, and Olig2, are significantly increased in the spinal dorsal horn of HIV patients who developed chronic pain. The levels of myelin proteins myelin basic protein and proteolipid protein are also aberrant in the spinal dorsal horn of "pain-positive" HIV patients. Similarly, the oligodendrocyte and myelin markers are up-regulated in the spinal dorsal horn of a mouse model of HIV-1 gp120-induced pain. Surprisingly, the expression of gp120-induced mechanical allodynia appears intact up to 4 h after myelin basic protein is knocked down or knocked out.. These findings suggest that oligodendrocytes are reactive during the pathogenesis of HIV-associated pain. However, interfering with myelination does not alter the induction of gp120-induced pain.

Topics: Animals; Biomarkers; Gene Knockdown Techniques; HIV Envelope Protein gp120; HIV Infections; Humans; Hyperalgesia; Mice, Inbred C57BL; Mice, Knockout; Myelin Basic Protein; Myelin Sheath; Oligodendroglia; Pain; Spinal Cord Dorsal Horn; Up-Regulation

Neuropathic pain is a debilitating condition in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Specific myelin basic protein (MBP) peptides are encephalitogenic, and myelin-derived altered peptide ligands (APLs) are capable of preventing and ameliorating EAE. We investigated the effects of active immunisation with a weakly encephalitogenic epitope of MBP (MBP87-99) and its mutant APL (Cyclo-87-99[A(91),A(96)]MBP87-99) on pain hypersensitivity and neuroinflammation in Lewis rats. MBP-treated rats exhibited significant mechanical and thermal pain hypersensitivity associated with infiltration of T cells, MHC class II expression and microglia activation in the spinal cord, without developing clinical signs of paralysis. Co-immunisation with APL significantly decreased pain hypersensitivity and neuroinflammation emphasising the important role of neuroimmune crosstalk in neuropathic pain.

Topics: Animals; Disease Models, Animal; Exploratory Behavior; Freund's Adjuvant; Histocompatibility Antigens Class II; Humans; Hypersensitivity; Ligands; Lymphocyte Activation; Male; Microglia; Myelin Basic Protein; Myelitis; Pain; Pain Measurement; Pain Threshold; Peptide Fragments; Rats; Rats, Inbred Lew; Spinal Cord; T-Lymphocytes; Time Factors; Vaccination

Tau protein hyperphosphorylation and consequent malfunction are hallmarks of Alzheimer's disease pathology; importantly, pain perception is diminished in these patients. In physiological conditions, Tau contributes to cytoskeletal dynamics and in this way, influences a number of cellular mechanisms including axonal trafficking, myelination and synaptic plasticity, processes that are also implicated in pain perception. However, there is no in vivo evidence clarifying the role of Tau in nociception. Thus, we tested Tau-null (Tau-/-) and Tau+/+ mice for acute thermal pain (Hargreaves' test), acute and tonic inflammatory pain (formalin test) and mechanical allodynia (Von Frey test). We report that Tau-/- animals presented a decreased response to acute noxious stimuli when compared to Tau+/+ while their pain-related behavior is augmented under tonic painful stimuli. This increased reactivity to tonic pain was accompanied by enhanced formalin-evoked c-fos staining of second order nociceptive neurons at Tau-null dorsal horn. In addition, we analyzed the primary afferents conveying nociceptive signals, estimating sciatic nerve fiber density, myelination and nerve conduction. Ultrastructural analysis revealed a decreased C-fiber density in the sciatic nerve of Tau-null mice and a hypomyelination of myelinated fibers (Aδ-fibers) - also confirmed by western blot analysis - followed by altered conduction properties of Tau-null sciatic nerves. To our knowledge, this is the first in vivo study that demonstrates that Tau depletion negatively affects the main systems conveying nociceptive information to the CNS, adding to our knowledge about Tau function(s) that might also be relevant for understanding peripheral neurological deficits in different Tauopathies.

Topics: Action Potentials; Analysis of Variance; Animals; Disease Models, Animal; Functional Laterality; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myelin Basic Protein; Nerve Fibers, Unmyelinated; Pain; Pain Measurement; Pain Threshold; Physical Stimulation; Proto-Oncogene Proteins c-fos; Sciatic Nerve; tau Proteins; Time Factors

The myelin sheath provides electrical insulation of mechanosensory Aβ-afferent fibers. Myelin-degrading matrix metalloproteinases (MMPs) damage the myelin sheath. The resulting electrical instability of Aβ-fibers is believed to activate the nociceptive circuitry in Aβ-fibers and initiate pain from innocuous tactile stimulation (mechanical allodynia). The precise molecular mechanisms, responsible for the development of this neuropathic pain state after nerve injury (for example, chronic constriction injury, CCI), are not well understood.. Using mass spectrometry of the whole sciatic nerve proteome followed by bioinformatics analyses, we determined that the pathways, which are classified as the Infectious Disease and T-helper cell signaling, are readily activated in the nerves post-CCI. Inhibition of MMP-9/MMP-2 suppressed CCI-induced mechanical allodynia and concomitant TNF-α and IL-17A expression in nerves. MMP-9 proteolysis of myelin basic protein (MBP) generated the MBP84-104 and MBP68-86 digest peptides, which are prominent immunogenic epitopes. In agreement, the endogenous MBP69-86 epitope co-localized with MHCII and MMP-9 in Schwann cells and along the nodes of Ranvier. Administration of either the MBP84-104 or MBP68-86 peptides into the naïve nerve rapidly produced robust mechanical allodynia with a concomitant increase in T cells and MHCII-reactive cell populations at the injection site. As shown by the genome-wide expression profiling, a single intraneural MBP84-104 injection stimulated the inflammatory, immune cell trafficking, and antigen presentation pathways in the injected naïve nerves and the associated spinal cords. Both MBP84-104-induced mechanical allodynia and characteristic pathway activation were remarkably less prominent in the T cell-deficient athymic nude rats.. These data implicate MBP as a novel mediator of pain. Furthermore, the action of MMPs expressed within 1 day post-injury is critical to the generation of tactile allodynia, neuroinflammation, and the immunodominant MBP digest peptides in nerve. These MBP peptides initiate mechanical allodynia in both a T cell-dependent and -independent manner. In the course of Wallerian degeneration, the repeated exposure of the cryptic MBP epitopes, which are normally sheltered from immunosurveillance, may induce the MBP-specific T cell clones and a self-sustaining immune reaction, which may together contribute to the transition of acute pain into a chronic neuropathic pain state.

Topics: Amino Acid Sequence; Animals; Epitopes, T-Lymphocyte; Female; HEK293 Cells; Humans; Immunodominant Epitopes; Molecular Sequence Data; Monitoring, Immunologic; Myelin Basic Protein; Pain; Pain Measurement; Rats; Rats, Nude; Rats, Sprague-Dawley; T-Lymphocyte Subsets

The expression of sodium channels (NaCh(s)) change after inflammatory and nerve lesions, and this change has been implicated in the generation of pain states. Here we examine NaCh expression within nerve fibers from normal and painful extracted human teeth with special emphasis on their localization within large accumulations, like those seen at nodes of Ranvier. Pulpal tissue sections from normal wisdom teeth and from teeth with large carious lesions associated with severe and spontaneous pain were double-stained with pan-specific NaCh antibody and caspr (paranodal protein used to visualize nodes of Ranvier) antibody, while additional sections were triple-stained with NaCh, caspr and myelin basic protein (MBP) antibodies. Z-series of images were obtained with the confocal microscope and evaluated with NIH ImageJ software to quantify the density and size of NaCh accumulations, and to characterize NaCh localization at caspr-identified typical and atypical nodal sites. Although the results showed variability in the overall density and size of NaCh accumulations in painful samples, a common finding included the remodeling of NaChs at atypical nodal sites. This remodeling of NaChs included prominent NaCh expression within nerve regions that showed a selective loss of MBP staining in a pattern consistent with a demyelinating process.. This study identifies the remodeling of NaChs at demyelinated sites within the painful human dental pulp and suggests that the contribution of NaChs to spontaneous pulpal pain generation may be dependant not only on total NaCh density but may also be related to NaCh expression at atypical nodal sites.

Topics: Adolescent; Adult; Axons; Cell Adhesion Molecules, Neuronal; Contactins; Demyelinating Diseases; Dental Pulp; Female; Humans; Immunohistochemistry; Male; Microscopy, Confocal; Molar, Third; Myelin Basic Protein; Myelin Sheath; Nerve Fibers; Pain; Ranvier's Nodes; Sodium Channels; Young Adult

Matrix metalloproteinases (MMPs) emerge as modulators of neuropathic pain. Because myelin protects Abeta afferents from ectopic hyperexcitability and nociception from innocuous mechanical stimuli (or mechanical allodynia), we analyzed the role of MMPs in the development of mechanical allodynia through myelin protein degradation after rat and MMP-9-/- mouse L5 spinal nerve crush (L5 SNC). MMPs were shown to promote selective degradation of myelin basic protein (MBP), with MMP-9 regulating initial Schwann cell-mediated MBP processing after L5 SNC. Acute and long-term therapy with GM6001 (broad-spectrum MMP inhibitor) protected from injury-induced MBP degradation, caspase-mediated apoptosis, macrophage infiltration in the spinal nerve and inhibited astrocyte activation in the spinal cord. The effect of GM6001 therapy on attenuation of mechanical allodynia was robust, immediate and sustained through the course of L5 SNC. In conclusion, MMPs mediate the initiation and maintenance of mechanical nociception through Schwann cell-mediated MBP processing and support of neuroinflammation.

Topics: Animals; Apoptosis; Behavior, Animal; Cell Survival; Dipeptides; Female; Matrix Metalloproteinase 2; Matrix Metalloproteinase 7; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Mice; Mice, Knockout; Myelin Basic Protein; Nerve Crush; Neuroglia; Pain; Pain Measurement; Protease Inhibitors; Rats; Rats, Sprague-Dawley; Schwann Cells; Spinal Nerves

Animal studies and a few human studies have shown a change in sodium channel (NaCh) expression after inflammatory lesions, and this change is implicated in the generation of pain states. We are using the extracted human tooth as a model system to study peripheral pain mechanisms and here examine the expression of the Nav1.7 NaCh isoform in normal and painful samples. Pulpal sections were labeled with antibodies against: 1) Nav1.7, N52 and PGP9.5, and 2) Nav1.7, caspr (a paranodal protein used to identify nodes of Ranvier), and myelin basic protein (MBP), and a z-series of optically-sectioned images were obtained with the confocal microscope. Nav1.7-immunofluorescence was quantified in N52/PGP9.5-identified nerve fibers with NIH ImageJ software, while Nav1.7 expression in myelinated fibers at caspr-identified nodal sites was evaluated and further characterized as either typical or atypical as based on caspr-relationships.. Results show a significant increase in nerve area with Nav1.7 expression within coronal and radicular fiber bundles and increased expression at typical and atypical caspr-identified nodal sites in painful samples. Painful samples also showed an augmentation of Nav1.7 within localized areas that lacked MBP, including those associated with atypical caspr-identified sites, thus identifying NaCh remodeling within demyelinating axons as the basis for a possible pulpal pain mechanism.. This study identifies the increased axonal expression and augmentation of Nav1.7 at intact and remodeling/demyelinating nodes within the painful human dental pulp where these changes may contribute to constant, increased evoked and spontaneous pain responses that characterize the pain associated with toothache.

Topics: Adult; Dental Pulp; Female; Humans; Immunohistochemistry; Male; Microscopy, Confocal; Middle Aged; Myelin Basic Protein; NAV1.7 Voltage-Gated Sodium Channel; Pain; Sodium Channels

Lysophosphatidic acid (LPA) causes neuropathic pain with demyelination in sensory fibers. In dorsal root (DR) ex vivo culture, the addition of 0.1 microM LPA caused a characteristic demyelination at 24h in scanning and transmission electron microscopy analyses. Moreover, direct contact between C-fibers due to loss of partition by Schwann cell in Remak bundles was observed. LPA-induced demyelination of DR was concentration-dependent in the range between 0.01 and 1M, and was abolished by BoNT/C3 and Y-27632, a RhoA and Rho kinase inhibitor, respectively. The demyelination was equivalent between the preparations with and without dorsal root ganglion. LPA also caused a down-regulation of myelin proteins, such as myelin basic protein (MBP) and myelin protein zero (MPZ) to approximately 70% of control. All these findings suggest that the demyelination observed in the neuropathic pain due to nerve injury occurs through a direct action of LPA on Schwann cells.

Topics: Animals; Blotting, Western; Cells, Cultured; Demyelinating Diseases; Hyperalgesia; Lysophospholipids; Male; Mice; Mice, Knockout; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Myelin Basic Protein; Myelin P0 Protein; Myelin Sheath; Nerve Fibers; Pain; Receptors, Lysophosphatidic Acid; Schwann Cells; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spinal Nerve Roots; Tolonium Chloride

We are characterizing toxicant-induced injury to the nervous system by measuring nervous system, cell-type specific proteins together with accompanying changes in morphology and behavior. In the present study, cerebellar neurotoxicity was assessed in the Gunn rat, an autosomal recessive mutant that exhibits degeneration of Purkinje cells due to hereditary hyperbilirubinemia. Five proteins associated with neuronal or glial cell types were chosen for evaluation as follows: G-substrate, a Purkinje cell-specific phosphoprotein that serves as the endogenous substrate of cyclic GMP-dependent protein kinase; PCPP-260, a Purkinje cell-specific phosphoprotein that serves as an endogenous substrate of cyclic AMP-dependent protein kinase; synapsin I, a synapse-specific phosphoprotein present in all neurons; glial fibrillary acidic protein, an astrocyte-specific protein; and myelin basic protein, a protein unique to myelin. In comparison to heterozygote (Jj) controls, homozygous (jj) rats showed alterations in the amounts of neurotypic and gliotypic proteins in cerebellum that were consistent with the neuropathological effects associated with development of hyperbilirubinemia in the Gunn rat. Decreased cerebellar cyclic GMP, but not cyclic AMP, alterations in indices of motoric competence and increased responsiveness to a nociceptive stimulus also were observed in jj rats. In general, the degree of cerebellar hypoplasia was predictive of the degree of biochemical, morphological or behavioral change observed. The results indicate that neurotypic and gliotyic proteins may be used as biochemical indicators of neurotoxicity.

Topics: Animals; Cerebellum; Cyclic AMP; Cyclic GMP; Glial Fibrillary Acidic Protein; Hyperbilirubinemia; Male; Molecular Weight; Motor Activity; Myelin Basic Protein; Nerve Tissue Proteins; Organ Size; Pain; Phosphorylation; Radioimmunoassay; Rats; Rats, Gunn; Synapsins