Oligodendrocytes: biology and pathology

Oligodendrocytes are the myelinating cells of the central nervous system (CNS). They are the end product of a cell lineage which has to undergo a complex and precisely timed program of proliferation, migration, differentiation, and myelination to finally produce the insulating sheath of axons. Due to this complex differentiation program, and due to their unique metabolism/physiology, oligodendrocytes count among the most vulnerable cells of the CNS. In this review, we first describe the different steps eventually culminating in the formation of mature oligodendrocytes and myelin sheaths, as they were revealed by studies in rodents. We will then show differences and similarities of human oligodendrocyte development. Finally, we will lay out the different pathways leading to oligodendrocyte and myelin loss in human CNS diseases, and we will reveal the different principles leading to the restoration of myelin sheaths or to a failure to do so

Racial differences in neuromyelitis optica spectrum disorder

OBJECTIVE:We aimed to evaluate racial differences in the clinical features of neuromyelitis optica spectrum disorder. METHODS:This retrospective review included 603 patients (304 Asian, 207 Caucasian, and 92 Afro-American/Afro-European), who were seropositive for anti-aquaporin-4 antibody, from 6 centers in Denmark, Germany, South Korea, United Kingdom, United States, and Thailand. RESULTS:Median disease duration at last follow-up was 8 years (range 0.3-38.4 years). Asian and Afro-American/Afro-European patients had a younger onset age than Caucasian patients (mean 36, 33, and 44 years, respectively; p < 0.001). During the disease course, Caucasian patients (23%) had a lower incidence of brain/brainstem involvement than Asian (42%) and Afro-American/Afro-European patients (38%) (p < 0.001). Severe attacks (visual acuity ≤0.1 in at least one eye or Expanded Disability Status Scale score ≥6.0 at nadir) at onset occurred more frequently in Afro-American/Afro-European (58%) than in Asian (46%) and Caucasian (38%) patients (p = 0.005). In the multivariable analysis, older age at onset, higher number of attacks before and after immunosuppressive treatment, but not race, were independent predictors of severe motor disabilities at last follow-up. CONCLUSION:A review of a large international cohort revealed that race affected the clinical phenotype, age at onset, and severity of attacks, but the overall outcome was most dependent on early and effective immunosuppressive treatment

Myelin injury without astrocytopathy in neuroinflammatory disorders with MOG antibodies.

Objective To compare myelin and astrocyte injury in patients with antibodies against myelin oligodendrocyte glycoprotein (anti-MOG) or aquaporin-4 (anti-AQP4), and multiple sclerosis (MS). Methods Myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) levels were measured in the cerebral spinal fluid (CSF) from anti-MOG+ or anti-AQP4+ patients tested in both sera and CSF by cell-based assays with live transfected cells. Results In total, 75.6% (68/90) of the patients were positive for either anti-MOG or anti-AQP4 antibodies in both serum and CSF; 74.2% (23/31) were anti-MOG+, and 76.3% (45/59) were anti-AQP4+. No patients were only CSF positive or were positive for both anti-MOG and anti-AQP4 antibodies, and none of the MS patients or controls had these autoantibodies in the serum or CSF. MBP levels were elevated in the anti-MOG+ cases compared to the multiple sclerosis (MS) patients, and the levels found were similar between anti-MOG+ cases and anti-AQP4+ neuromyelitis optica spectrum disorder (NMOSD) cases. Meanwhile, GFAP was only elevated in the anti-AQP4+ NMOSD. Moreover, CSF pleocytosis, high protein levels, and oligoclonal IgG band negativity distinguished the anti-MOG+ cases from MS patients. Conclusions Myelin injury was more severe in the anti-MOG+ cases than in the MS cases, and anti-MOG+ cases have differences in the CSF characteristics compared to MS. GFAP elevation in anti-AQP4+ cases was absent in anti-MOG+ patients (even in cases with NMOSD phenotype), indicating that immune-mediated astrocytopathy is unique to anti-AQP4+ patients. Our study suggests that anti-MOG+ cases are distinct from MS and anti-AQP4+ NMOSD.</p