myelin-oligodendrocyte-glycoprotein-(35-55) and Spinal-Cord-Injuries

Fibrotic scar tissue limits central nervous system regeneration in adult mammals. The extent of fibrotic tissue generation and distribution of stromal cells across different lesions in the brain and spinal cord has not been systematically investigated in mice and humans. Furthermore, it is unknown whether scar-forming stromal cells have the same origin throughout the central nervous system and in different types of lesions. In the current study, we compared fibrotic scarring in human pathological tissue and corresponding mouse models of penetrating and non-penetrating spinal cord injury, traumatic brain injury, ischemic stroke, multiple sclerosis and glioblastoma. We show that the extent and distribution of stromal cells are specific to the type of lesion and, in most cases, similar between mice and humans. Employing in vivo lineage tracing, we report that in all mouse models that develop fibrotic tissue, the primary source of scar-forming fibroblasts is a discrete subset of perivascular cells, termed type A pericytes. Perivascular cells with a type A pericyte marker profile also exist in the human brain and spinal cord. We uncover type A pericyte-derived fibrosis as a conserved mechanism that may be explored as a therapeutic target to improve recovery after central nervous system lesions.

Topics: Aging; Animals; Astrocytes; Brain Injuries, Traumatic; Brain Ischemia; Brain Neoplasms; Central Nervous System; Cerebral Cortex; Cicatrix; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Extracellular Matrix; Fibroblasts; Fibrosis; Glioblastoma; Humans; Ischemic Stroke; Mice, Inbred C57BL; Mice, Transgenic; Myelin-Oligodendrocyte Glycoprotein; Peptide Fragments; Pericytes; Receptor, Platelet-Derived Growth Factor beta; Spinal Cord; Spinal Cord Injuries; Stromal Cells

The preclinical selection of therapeutic candidates for progressive multiple sclerosis (MS) would be aided by the development of sensitive behavioural measures that accurately reflect the impact of autoimmune-mediated spinal cord damage on locomotion. Neurological deficits in mice subjected to experimental autoimmune encephalomyelitis (EAE) are typically scored using a clinical scale with 5-10 levels of increased disease severity. This ordinal scale represents a general impression of paralysis and impaired gait. By contrast, kinematic gait analyses generate ratio level data that have frequently been used to characterize walking deficits for MS patients and test the efficacy of treatments designed to improve them. Despite these advantages, kinematic gait analyses have not been systematically applied to the study of walking deficits for EAE mice. We have therefore used high speed video recordings (250 frames/s) of EAE mice walking on a treadmill to measure 8 kinematic parameters in the sagittal plane: average hip height (1), average toe height during swing (2), and average angle and range of motion for the hip (3-4), knee (5-6) and ankle (7-8). Kinematic measures of hip, knee and ankle movements were found to be early detectors of impaired locomotion for mice with mild EAE (median clinical score=1.0 at day post-immunization 26; DPI 26). These deficits occurred in the absence of reduced rotarod performance with impaired hip and knee movements observed 3days before disease onset as determined by clinical scores. Gait deficits for mild EAE mice were minor and often recovered fully by DPI 30. By contrast, severe EAE mice (median clinical score=2.5 at DPI 26) displayed much larger movement impairments for the knee and ankle that failed to completely recover by DPI 44. Moreover, impaired ankle movement was highly correlated with white matter loss in the spinal cords of EAE mice (r=0.96). Kinematic analyses therefore yield highly sensitive measures of motor deficits that predict spinal cord injury in EAE mice. These behavioural techniques should assist the selection of promising therapeutic candidates for clinical testing in progressive MS.

Topics: Animals; Ankle; Biomechanical Phenomena; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Female; Freund's Adjuvant; Gait; Hip; Locomotion; Mice; Mice, Inbred C57BL; Motor Disorders; Myelin-Oligodendrocyte Glycoprotein; Peptide Fragments; Pertussis Toxin; Range of Motion, Articular; Rotarod Performance Test; Spinal Cord Injuries

Monocyte-derived macrophages (mo-MΦs) and T cells have been shown to contribute to spinal cord repair. Recently, the remote brain choroid plexus epithelium (CP) was identified as a portal for monocyte recruitment, and its activation for leukocyte trafficking was found to be IFN-γ-dependent. Here, we addressed how the need for effector T cells can be reconciled with the role of inflammation-resolving immune cells in the repair process. Using an acute spinal cord injury model, we show that in mice deficient in IFN-γ-producing T cells, the CP was not activated, and recruitment of inflammation-resolving mo-MΦ to the spinal cord parenchyma was limited. We further demonstrate that mo-MΦ locally regulated recruitment of thymic-derived Foxp3(+) regulatory T (Treg) cells to the injured spinal cord parenchyma at the subacute/chronic phase. Importantly, an ablation protocol that resulted in reduced Tregs at this stage interfered with tissue remodeling, in contrast to Treg transient ablation, restricted to the 4 d period before the injury, which favored repair. The enhanced functional recovery observed following such a controlled decrease of Tregs suggests that reduced systemic immunosuppression at the time of the insult can enhance CNS repair. Overall, our data highlight a dynamic immune cell network needed for repair, acting in discrete compartments and stages, and involving effector and regulatory T cells, interconnected by mo-MΦ. Any of these populations may be detrimental to the repair process if their level or activity become dysregulated. Accordingly, therapeutic interventions must be both temporally and spatially controlled.

Topics: Animals; Antigens, CD; CD11c Antigen; CX3C Chemokine Receptor 1; Diphtheria Toxin; Disease Models, Animal; Forkhead Transcription Factors; Green Fluorescent Proteins; Humans; Macrophages; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myelin-Oligodendrocyte Glycoprotein; Nerve Regeneration; Peptide Fragments; Receptors, Chemokine; Recovery of Function; Spinal Cord Injuries; T-Box Domain Proteins; T-Lymphocytes, Regulatory; Vaccination

Our previous studies showed that ligands to type 2 imidazoline receptors (I₂R), including 2-(2-Benzofuranyl)-2-imidazoline (2-BFI) and Idazoxan, were effective in reducing spinal cord inflammation caused by experimental autoimmune encephalomyelitis (EAE). In the present study, we determined the effective therapeutic time window of 2-BFI and found that administration of 2-BFI in mice before the appearance of ascending flaccid paralysis (1-10 days post immunization), but not during the period when neurological deficits occurred (11-20 days post immunization), significantly ameliorated EAE-induced neurobehavioral deficits, reduced the infiltration of inflammatory cells into the spinal cord, and reduced the level of demyelination. More interestingly, giving 2-BFI during 1-10 days post immunization selectively suppressed IL-17 levels in the peripheral blood, which strongly suggests that IL-17 may be a good early marker to indicate EAE progression and that 2-BFI may target CD4⁺ T lymphocytes, especially Th17 cells to reduce IL-17 expression. Collectively, these studies led us to envisage that 2-BFI can be a useful drug to treat multiple sclerosis (MS) when used in combination with an early indicator of MS progression, such as IL-17.

Topics: Analysis of Variance; Animals; Benzofurans; Calcium-Binding Proteins; Cytokines; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Enzyme-Linked Immunosorbent Assay; Freund's Adjuvant; Imidazoles; Indoles; Mice; Mice, Inbred C57BL; Microfilament Proteins; Myelin Sheath; Myelin-Oligodendrocyte Glycoprotein; Nervous System Diseases; Peptide Fragments; Spinal Cord Injuries; Time Factors

Although macrophages (MPhi) are known as essential players in wound healing, their contribution to recovery from spinal cord injury (SCI) is a subject of debate. The difficulties in distinguishing between different MPhi subpopulations at the lesion site have further contributed to the controversy and led to the common view of MPhi as functionally homogenous. Given the massive accumulation in the injured spinal cord of activated resident microglia, which are the native immune occupants of the central nervous system (CNS), the recruitment of additional infiltrating monocytes from the peripheral blood seems puzzling. A key question that remains is whether the infiltrating monocyte-derived MPhi contribute to repair, or represent an unavoidable detrimental response. The hypothesis of the current study is that a specific population of infiltrating monocyte-derived MPhi is functionally distinct from the inflammatory resident microglia and is essential for recovery from SCI.. We inflicted SCI in adult mice, and tested the effect of infiltrating monocyte-derived MPhi on the recovery process. Adoptive transfer experiments and bone marrow chimeras were used to functionally distinguish between the resident microglia and the infiltrating monocyte-derived MPhi. We followed the infiltration of the monocyte-derived MPhi to the injured site and characterized their spatial distribution and phenotype. Increasing the naïve monocyte pool by either adoptive transfer or CNS-specific vaccination resulted in a higher number of spontaneously recruited cells and improved recovery. Selective ablation of infiltrating monocyte-derived MPhi following SCI while sparing the resident microglia, using either antibody-mediated depletion or conditional ablation by diphtheria toxin, impaired recovery. Reconstitution of the peripheral blood with monocytes resistant to ablation restored the lost motor functions. Importantly, the infiltrating monocyte-derived MPhi displayed a local anti-inflammatory beneficial role, which was critically dependent upon their expression of interleukin 10.. The results of this study attribute a novel anti-inflammatory role to a unique subset of infiltrating monocyte-derived MPhi in SCI recovery, which cannot be provided by the activated resident microglia. According to our results, limited recovery following SCI can be attributed in part to the inadequate, untimely, spontaneous recruitment of monocytes. This process is amenable to boosting either by active vaccination with a myelin-derived altered peptide ligand, which indicates involvement of adaptive immunity in monocyte recruitment, or by augmenting the naïve monocyte pool in the peripheral blood. Thus, our study sheds new light on the long-held debate regarding the contribution of MPhi to recovery from CNS injuries, and has potentially far-reaching therapeutic implications.

Topics: Adoptive Transfer; Animals; Glycoproteins; Inflammation; Interleukin-10; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Monocytes; Myelin-Oligodendrocyte Glycoprotein; Ovalbumin; Peptide Fragments; Spinal Cord; Spinal Cord Injuries