Serotonergic neuronal sprouting as a potential mechanism of recovery in multiple sclerosis

Temporal and spatial evolution of various functional neurons during demyelination induced by cuprizone

Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS). Here we report the temporal and spatial evolution of various functional neurons during demyelination in a cuprizone (CPZ)-induced mouse model. CPZ did not significantly induce the damage of axons and neurons after 2 wk of feeding. However, after 4-6 wk of CPZ feeding, axons and neurons were markedly reduced in the cortex, posterior thalamic nuclear group, and hippocampus. Simultaneously, the expression of TPH⁺ tryptophan neurons and VGLUT1⁺ glutamate neurons was obviously decreased, and the expression of TH⁺ dopaminergic neurons was slightly decreased in the tail part of the substantia nigra striatum, whereas the number of ChAT⁺ cholinergic neurons was not significantly different in the brain. In the second week of feeding, CPZ caused a higher level of glutamate secretion and upregulated the expression of EAAT2 on astrocytes, which should contribute to rapid and sufficient glutamate uptake and removal. This finding reveals that astrocyte-driven glutamate reuptake protected the CNS from excitotoxicity by rapid reuptake of glutamate in 4-6 wk of CPZ feeding. At this stage, although NG2⁺ oligodendroglia progenitor cells (OPCs) were enhanced in the demyelination foci, the myelin sheath was still absent. In conclusion, we comprehensively observed the temporal and spatial evolution of various functional neurons. Our results will assist with understanding how demyelination affects neurons during CPZ-induced demyelination and provide novel information for neuroprotection in myelin regeneration and demyelinating diseases.NEW & NOTEWORTHY Our results further indicate temporal and spatial evolution of various functional neurons during the demyelination in a cuprizone (CPZ)-induced mouse model, which mainly occur 4-6 wk after CPZ feeding. At the same time, the axonal compartment is damaged and, consequently, neuronal death occurs, while glutamate neurons are lost obviously. The astrocyte-mediated glutamate reuptake could protect the neurons from the excitatory effects of glutamate.

Multiple sclerosis is associated with high trait anger: a case-control study

INTRODUCTION

In recent years there has been a focus on health-related quality of life in multiple sclerosis (MS) and in particular the importance of non-motor problems such as fatigue, pain, depression, anxiety, and cognitive disorders. However, little attention has been focused on other negative emotions, such as anger. Our purpose was to evaluate whether trait anger (a predisposition to experience frequent and intense episodes of anger over time) is different between persons with and without MS after controlling for depression, anxiety, and other socio-demographic variables.

METHODS

157 consecutive MS patients were enrolled in the study and compared to eighty age, gender, and education-matched healthy controls. Participants were administered affective trait measures (Beck Depression Inventory, Beck Anxiety Inventory) and the trait anger measure (the Spanish adapted version of the State-Trait Anger Expression Inventory-2 [STAXI-2]).

RESULTS

MS patients had significantly higher scores on anger intensity (state anger) and trait anger than did controls. They also had a trend to experience direct anger toward other persons or objects in the environment (higher anger expression-out score) and to hold in or suppress angry feelings (higher anger expression-in score). However, in a regression analysis that adjusted for different demographic and clinical variables, we found that diagnosis category (MS patient vs. control) was associated with none of the highest quartiles of STAXI-2 scores, except for the Trait Anger scale (odds ratios between 2.35 and 3.50).

CONCLUSIONS

The present study provides further evidence that MS is independently associated with high trait anger.

Neuroendocrine immunoregulation in multiple sclerosis

Currently, it is generally accepted that multiple sclerosis (MS) is a complex multifactorial disease involving genetic and environmental factors affecting the autoreactive immune responses that lead to damage of myelin. In this respect, intrinsic or extrinsic factors such as emotional, psychological, traumatic, or inflammatory stress as well as a variety of other lifestyle interventions can influence the neuroendocrine system. On its turn, it has been demonstrated that the neuroendocrine system has immunomodulatory potential. Moreover, the neuroendocrine and immune systems communicate bidirectionally via shared receptors and shared messenger molecules, variously called hormones, neurotransmitters, or cytokines. Discrepancies at any level can therefore lead to changes in susceptibility and to severity of several autoimmune and inflammatory diseases. Here we provide an overview of the complex system of crosstalk between the neuroendocrine and immune system as well as reported dysfunctions involved in the pathogenesis of autoimmunity, including MS. Finally, possible strategies to intervene with the neuroendocrine-immune system for MS patient management will be discussed. Ultimately, a better understanding of the interactions between the neuroendocrine system and the immune system can open up new therapeutic approaches for the treatment of MS as well as other autoimmune diseases.

Effects of vaccination with altered Peptide ligand on chronic pain in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis

Neuropathic pain is a chronic symptom of multiple sclerosis (MS) and affects nearly half of all MS sufferers. A key instigator of this pain is the pro-inflammatory response in MS. We investigated the behavioral effects of immunization with a mutant peptide of myelin basic protein (MBP), termed altered peptide ligand (APL), known to initiate immune deviation from a pro-inflammatory state to an anti-inflammatory response in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Male and female Lewis rats were injected with vehicle control or with varying doses of 50 or 100 μg guinea pig MBP in combination with or without APL. APL-treated animals established significantly lower disease severity compared to encephalitogenic MBP-treated animals. Animals with EAE developed mechanical, but not thermal pain hypersensitivity. Mechanical pain sensitivities were either improved or normalized during periods of clinical disease in male and female APL-treated animals as compared to the encephalitogenic group. No significant changes to thermal latency were observed upon co-immunization with APL. Together these data indicate that APL ameliorates disease states and selectively mediates an analgesic effect on EAE animals.

Resting-state functional connectivity in multiple sclerosis: an examination of group differences and individual differences

Multiple sclerosis (MS) is a neurodegenerative, inflammatory disease of the central nervous system, resulting in physical and cognitive disturbances. The goal of the current study was to examine the association between network integrity and composite measures of cognition and disease severity in individuals with relapsing-remitting MS (RRMS), relative to healthy controls. All participants underwent a neuropsychological and neuroimaging session, where resting-state data was collected. Independent component analysis and dual regression were employed to examine network integrity in individuals with MS, relative to healthy controls. The MS sample exhibited less connectivity in the motor and visual networks, relative to healthy controls, after controlling for group differences in gray matter volume. However, no alterations were observed in the frontoparietal, executive control, or default-mode networks, despite previous evidence of altered neuronal patterns during tasks of exogenous processing. Whole-brain, voxel-wise regression analyses with disease severity and processing speed composites were also performed to elucidate the brain-behavior relationship with neuronal network integrity. Individuals with higher levels of disease severity demonstrated reduced intra-network connectivity of the motor network, and the executive control network, while higher disease burden was associated with greater inter-network connectivity between the medial visual network and areas involved in visuomotor learning. Our findings underscore the importance of examining resting-state oscillations in this population, both as a biomarker of disease progression and a potential target for therapeutic intervention.

Lifetime and actual prevalence of pain and headache in multiple sclerosis

The aim of the present study is to assess the actual and lifetime frequency of neuropathic (trigeminal neuralgia, Lhermitte’s sign, dysesthesic pain) and somatic (painful muscle spasms and low back pain) pain and headache (tensive headache and migraine) in a cross-sectional sample of 428 consecutive multiple sclerosis (MS) outpatients followed-up in an Italian University MS center over a 3-month period. The impact of demographic and disease-related variables on pain and headache risk is also studied. A semi-structured questionnaire was administered during a face-to-face interview with MS patients and a multivariate logistic regression model is applied to obtain crude and adjusted risk measures. The mean age of the sample was 38.4 years, and female/male ratio was 1.65. The mean disease duration was 9.6 years and the median Expanded Disability Status Scale was 2.0, with most of the patients (74.8%) being affected by the relapsing–remitting form. Lifetime prevalence at the date of examination of at least one type of neuropathic or somatic pain was 39.8% in MS patients, with 58.5% also including headache, while the actual prevalence was 23.8% and 39.9%, respectively. After multivariate analysis, a progressive course of disease was shown to increase the risk of dysesthesic pain and painful muscle spasms, while greater disability was responsible for a higher risk of back pain. L’Hermitte’s sign was more frequent in younger patients, while females had a higher risk of headache. Pain and headache in MS are not negligible symptoms and a neurological examination should not miss the assessment of risk factors for specific types of pain for a more specific and individualized treatment.

Regeneration of nigrostriatal dopaminergic axons by degradation of chondroitin sulfate is accompanied by elimination of the fibrotic scar and glia limitans in the lesion site

Chondroitin sulfate increases around a lesion site after central nervous system injury and is believed to be an impediment to axonal regeneration, because administration of chondroitinase ABC, a chondroitin sulfate-degrading enzyme, promotes axonal regeneration of central neurons. To examine the physiological role of chondroitin sulfate up-regulation after injury, the nigrostriatal dopaminergic axons were unilaterally transected in mice, and chondroitinase ABC was then injected into the lesion site. In mice transected only, tyrosine hydroxylase-immunoreactive axons did not extend across the lesion at 1 or 2 weeks after the transection. Immunoreactivities of chondroitin sulfate side chains and core protein of NG2 proteoglycan increased in and around the lesion site, and a fibrotic scar containing type IV collagen deposits developed in the lesion center. In contrast, in mice transected and treated with chondroitinase ABC, numerous tyrosine hydroxylase-immunoreactive axons were regenerated across the lesion at 1 and 2 weeks after the transection. In these animals, chondroitin sulfate immunoreactivity remarkably decreased, and immunoreactivity of 2B6 antibody, which recognizes the stub of degraded chondroitin sulfate side chains, was enhanced. Furthermore, the formation of a fibrotic scar and a glia limitans that surrounds the former was completely prevented, although type IV collagen immunoreactivity remained in newly formed blood capillaries around the lesion site. We discuss the question of whether the chondroitin sulfate is acting as a direct inhibitor of axonal regeneration or whether the observed changes are due to a prevention of the fibrotic scar formation and a rearrangement of astrocytic membranes.

CD24 on the Resident Cells of the Central Nervous System Enhances Experimental Autoimmune Encephalomyelitis

CD24 is a cell surface glycoprotein that is expressed on both immune cells and cells of the CNS. We have previously shown that CD24 is required for the induction of experimental autoimmune encephalomyelitis (EAE), an experimental model for the human disease multiple sclerosis (MS). The development of EAE requires CD24 expression on both T cells and non-T host cells in the CNS. To understand the role of CD24 on the resident cells in the CNS during EAE development, we created CD24 bone marrow chimeras and transgenic mice in which CD24 expression was under the control of a glial fibrillary acidic protein promotor (AstroCD24TG mice). We showed that mice lacking CD24 expression on the CNS resident cells developed a mild form of EAE; in contrast, mice with overexpression of CD24 in the CNS developed severe EAE. Compared with nontransgenic mice, the CNS of AstroCD24TG mice had higher expression of cytokine genes such as IL-17 and demyelination-associated marker P8; the CNS of AstroCD24TG mice accumulated higher numbers of Th17 and total CD4+ T cells, whereas CD4+ T cells underwent more proliferation during EAE development. Expression of CD24 in CD24-deficient astrocytes also enhanced their costimulatory activity to myelin oligodendrocyte glycoprotein-specific, TCR-transgenic 2D2 T cells. Thus, CD24 on the resident cells in the CNS enhances EAE development via costimulation of encephalitogenic T cells. Because CD24 is increased drastically on resident cells in the CNS during EAE, our data have important implications for CD24-targeted therapy of MS.

Temporal pattern of plasma membrane calcium ATPase 2 expression in the spinal cord correlates with the course of clinical symptoms in two rodent models of autoimmune encephalomyelitis

Axonal/neuronal pathology is an important and early feature of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). However, the underlying molecular mechanisms remain elusive. We have previously reported that the levels of an important neuronal calcium pump, plasma membrane calcium ATPase 2 and synaptic proteins, synapsin IIa and syntaxin 1B are decreased in the rat spinal cord at onset of acute EAE. Whether the expression of these genes is restored during neurological recovery and affected in other EAE models is currently unknown. The present study was undertaken to address these issues by use of validated multiplex quantitative real-time RT-PCR with fluoro-primers, western blot and immunocytochemistry. We report that plasma membrane calcium ATPase 2 (PMCA2) transcript and protein levels return to control values during recovery from acute disease in the Lewis rat, whereas they are reduced throughout the course of chronic, non-remitting EAE in the C57Bl/6 mouse. These results indicate a close correlation between PMCA2 levels and disease course as defined by clinical scores reflecting motor deficits. Decrease in synapsin IIa expression also correlated with the onset and progression of neurological symptoms, whereas the pattern of syntaxin 1B mRNA and protein expression suggested post-transcriptional regulation. The decrease in PMCA2 transcript and protein levels and the correlation between expression and disease course in two different EAE models further highlight the importance of this calcium pump in neuronal dysfunction during inflammation.

Spinal motoneurone distress during experimental allergic encephalomyelitis

The main pathophysiological feature characterizing multiple sclerosis (MS) is demyelination. However, the possibility of neural damage has recently been proposed as a mechanism in chronic disease. Experimental allergic encephalomyelitis (EAE) is the most widely used experimental model for MS. We investigated occurrences of microglial activation and astrocytosis in the spinal cord, choline acetyl‐transferase (ChAT) and calcitonin gene‐related peptide (CGRP) mRNA regulation in spinal motoneurones during EAE. EAE was induced in female Lewis rats by injecting guinea pig spinal cord tissue in complete Freund's adjuvant (CFA) to which heat‐inactivated Mycobacterium had been added. Rats injected with CFA and uninjected rats were used as controls. ChAT and CGRP mRNAs were studied by in situ hybridization in the lumbar spinal cord and a computerized grain counting procedure was used for quantification. No differences in ChAT mRNA level were found between control and CFA‐injected rats. ChAT mRNA level was strongly reduced in EAE 14 days after immunization and then recovered (29 days after immunization). CGRP mRNA increased 14 days after immunization, and then recovered to control level. Extensive long‐lasting gliosis developed in the spinal cord and around motoneurones and a transient expression of p75^LNGFR in motoneurones was also found. These data suggest that during EAE, gliosis induces distress in spinal cord neurones involving the synthesis enzyme for the main transmitter.

Hyperalgesia in an animal model of multiple sclerosis

Many individuals with multiple sclerosis (MS) experience clinically significant pain, yet the underlying neural mechanisms for MS pain are not understood. Experimental autoimmune encephalomyelitis (EAE) is a well-studied disease in rodents that mimics many clinical and pathological features of MS, including central nervous system inflammation and demyelination. To determine whether EAE is an appropriate model for MS-related pain, nociceptive responses in both male and female SJL mice were measured before and after immunization with myelin proteolipid protein peptide 139-151 (PLP(139-151)) in complete Freund's adjuvant to induce 'active' EAE. To determine if changes in nociception were due to direct effects of encephalitogenic T cells, nociceptive responses in female SJL mice were measured following the transfer of activated, PLP(139-151) specific T cells to induce 'passive' EAE. Both forepaw and tail withdrawal latencies to a radiant heat stimulus were measured. In both active and passive EAE, there was an initial increase in tail withdrawal latency (hypoalgesia) that peaked several days prior to the peak in motor deficits during the acute disease phase. During the chronic disease phase, tail withdrawal latencies decreased and were significantly faster than control latencies for up to 38 days post-immunization. This hyperalgesia was seen in both sexes and in both active and passive EAE models. Forepaw withdrawal latencies remained within 1-2 s of baseline latencies for the entire testing period, indicating that the hypoalgesia and hyperalgesia were most pronounced in clinically affected body regions. These results suggest that both active and passive EAE are useful models of MS-related pain.

Administration of the 5-hydroxytryptamine(1A) receptor antagonist WAY100635 suppresses acute experimental allergic encephalomyelitis in Lewis rats

Experimental allergic encephalomyelitis (EAE) is a T-cell inflammatory disease of the central nervous system (CNS) widely considered as an animal model of multiple sclerosis. In Lewis rats, myelin basic protein-complete Freund's adjuvant (MBP-CFA)-induced EAE is an acute monophasic disease from which animals recover fully. In our experiments, daily treatment (since day 1 after MBP-CFA inoculation) with the 5-hydroxytryptamine((1A)) (5-HT(1A)) receptor agonist (R)-(+)-8-hydroxy-2-(Dipropylamino)-tetralin (R(+)-8-OH-DPAT) resulted in a dose-related enhancement of neurological and histological signs in EAE-induced rats. This effect of R(+)-8-OH-DPAT was reduced by the co-administration of the 5-HT(1A) receptor antagonist (N-[2-(4-[2-mehoxyphenil]-1-piperazinyl)-ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY100635) at the peak of the acute disease. Moreover, treatment with WAY100635 since inoculation resulted in a delayed onset of the first clinical signs, milder disease and earlier regression of neurological signs along with a decrease in inflammation in the CNS.