The road to remyelination in demyelinating diseases: current status and prospects for clinical treatment

Renal Outcome of IgM Nephropathy: A Comparative Prospective Cohort Study

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulonephritis characterized by diffuse deposits of IgM in the glomerular mesangium. However, its renal prognosis remains unknown. We compared renal outcomes of IgMN patients with those of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or mesangial proliferative glomerulonephritis (MsPGN) from a prospective observational cohort, with 1791 patients undergoing native kidney biopsy in eight hospitals affiliated with The Catholic University of Korea between December 2014 and October 2020. IgMN had more mesangial proliferation and matrix expansion than MsPGN and more tubular atrophy and interstitial fibrosis than MCD. IgMN patients had decreased eGFR than MCD patients in the earlier follow-up. However, there was no significant difference in urine protein or eGFR among all patients at the last follow-up. When IgMN was divided into three subtypes, patients with FSGS-like IgMN tended to have lower eGFR than those with MCD-like or MsPGN-like IgMN but higher proteinuria than MsPGN-like IgMN without showing a significant difference. The presence of hypertension at the time of kidney biopsy predicted ≥20% decline of eGFR over two years in IgMN patients. Our data indicate that IgMN would have a clinical course and renal prognosis similar to MCD, FSGS, and MsPGN.

Particles Containing Cells as a Strategy to Promote Remyelination in Patients With Multiple Sclerosis

The repair of demyelinated lesions is a key objective in multiple sclerosis research. Remyelination fundamentally depends on oligodendrocyte progenitor cells (OPC) reaching the lesion; this is influenced by numerous factors including age, disease progression time, inflammatory activity, and the pool of OPCs available, whether they be NG2 cells or cells derived from neural stem cells. Administering OPCs has been proposed as a potential cell therapy; however, these cells can only be administered directly. This article discusses the potential administration of OPCs encapsulated within hydrogel particles composed of biocompatible biomaterials, via the nose-to-brain pathway. We also discuss conditions for the indication of this therapy, and such related issues as the influence on endogenous remyelination, migration of OPCs to demyelinated areas, and the immune response, given the autoimmune nature of multiple sclerosis. Chitosan and derivatives constitute the most promising biomaterial for this purpose, although these issues must be addressed. In conclusion, this line of research may yield an alternative to the remyelinating drugs currently being studied.

Non-canonical B cell functions in transplantation

B cells are differentiated to recognize antigen and respond by producing antibodies. These activities, governed by recognition of ancillary signals, defend the individual against microorganisms and the products of microorganisms and constitute the canonical function of B cells. Despite the unique differentiation (e.g. recombination and mutation of immunoglobulin gene segments) toward this canonical function, B cells can provide other, "non-canonical" functions, such as facilitating of lymphoid organogenesis and remodeling and fashioning T cell repertoires and modifying T cell responses. Some non-canonical functions are exerted by antibodies, but most are mediated by other products and/or direct actions of B cells. The diverse set of non-canonical functions makes the B cell as much as any cell a central organizer of innate and adaptive immunity. However, the diverse products and actions also confound efforts to weigh the importance of individual non-canonical B cell functions. Here we shall describe the non-canonical functions of B cells and offer our perspective on how those functions converge in the development and governance of immunity, particularly immunity to transplants, and hurdles to advancing understanding of B cell functions in transplantation.

Timing of Future Remyelination Therapies and Their Potential to Stop Multiple Sclerosis Progression

Prior to the onset of demyelination in multiple sclerosis (MS), early oligodendrocyte injury, axonal degeneration and astroglial scarring occur. The irreversible progressive phase of MS begins when the axonal loss threshold is reached. Progressive disease onset has the highest impact on a poor prognosis in MS. Conversion to progressive disease is essentially an age-dependent process independent of disease duration and initial disease course. Although prevention of relapses has been the primary approach in the disease management, incomplete recovery from even the first relapse correlates with the long-term neurodegenerative phenotype of progressive MS onset. Therefore, the provider should review each patient's potential for relapse-related disability and start DMDs with the goal of preventing relapses. Existing immunomodulatory medications used to prevent MS relapses do not prevent long-term disability, which requires agents focused on remyelination and axonal repair. If applied immediately after a relapse rather than during the progressive phase of MS, remyelination-stimulating strategies may result in full recovery and prevention of long-term neurodegeneration and progressive disease course.

"A new imaging modality to non-invasively assess multiple sclerosis pathology"

We describe a novel imaging method to assess central nervous system pathology called "Diffusion Basis Spectrum Imaging" (DBSI). Diffusion tensor imaging (DTI) has been widely used to estimate axonpathology and demyelination. However, in the settings of acute inflammation and chronic tissue loss asare common in multiple sclerosis, DTI signals can lead to false interpretations. DBSI is a computationallynovel method that separates isotropic from anisotropic components in imaging voxels. Isotropicdiffusion is believed to reflect inflammatory components (cells, edema), as well as intrinsic cells andextracellular space. DBSI enables the measurement of axial and radial diffusivities within the anisotropiccomponents of imaging voxels, which reflect the integrity of axon fibers and myelin, respectively.

IgM in the kidney: a multiple personality disorder

IgM in the blood of normal individuals consists mainly of 'natural' polyreactive antibodies. Natural IgM is thought to provide an initial defense against infection and to promote the healing of wounded cells. Yet, as Panzer and colleagues show, these benefits can be eclipsed when the IgM binds to damaged cells of the glomerulus, activating complement. IgM in glomeruli thus signifies cellular damage and may warn that the pace of that damage exceeds the capacity for repair.

Applying an Open-Source Segmentation Algorithm to Different OCT Devices in Multiple Sclerosis Patients and Healthy Controls: Implications for Clinical Trials

Background. The lack of segmentation algorithms operative across optical coherence tomography (OCT) platforms hinders utility of retinal layer measures in MS trials. Objective. To determine cross-sectional and longitudinal agreement of retinal layer thicknesses derived from an open-source, fully-automated, segmentation algorithm, applied to two spectral-domain OCT devices. Methods. Cirrus HD-OCT and Spectralis OCT macular scans from 68 MS patients and 22 healthy controls were segmented. A longitudinal cohort comprising 51 subjects (mean follow-up: 1.4 ± 0.9 years) was also examined. Bland-Altman analyses and interscanner agreement indices were utilized to assess agreement between scanners. Results. Low mean differences (-2.16 to 0.26 μm) and narrow limits of agreement (LOA) were noted for ganglion cell and inner and outer nuclear layer thicknesses cross-sectionally. Longitudinally we found low mean differences (-0.195 to 0.21 μm) for changes in all layers, with wider LOA. Comparisons of rate of change in layer thicknesses over time revealed consistent results between the platforms. Conclusions. Retinal thickness measures for the majority of the retinal layers agree well cross-sectionally and longitudinally between the two scanners at the cohort level, with greater variability at the individual level. This open-source segmentation algorithm enables combining data from different OCT platforms, broadening utilization of OCT as an outcome measure in MS trials.

Established and novel disease-modifying treatments in multiple sclerosis

Multiple sclerosis (MS) is a presumed autoimmune disorder of the central nervous system, resulting in inflammatory demyelination and axonal and neuronal injury. New diagnostic criteria that incorporate magnetic resonance imaging have resulted in earlier and more accurate diagnosis of MS. Several immunomodulatory and immunosuppressive therapeutic agents are available for relapsing forms of MS, which allow individualized treatment based upon the benefits and risks. Disease-modifying therapies introduced in the 1990s, the beta-interferons and glatiramer acetate, have an established track record of efficacy and safety, although they require administration via injection. More recently, monoclonal antibodies have been engineered to act through specific mechanisms such as blocking alpha-4 integrin interactions (natalizumab) or lysing cells bearing specific markers, for example CD52 (alemtuzumab) or CD20 (ocrelizumab and ofatumumab). These agents can be highly efficacious, but sometimes have serious potential complications (natalizumab is associated with progressive multifocal leukoencephalopathy; alemtuzumab is associated with the development of new autoimmune disorders). Three new oral therapies (fingolimod, teriflunomide and dimethyl fumarate, approved for MS treatment from 2010 onwards) provide efficacy, tolerability and convenience; however, as yet, there are no long-term postmarketing efficacy and safety data in a general MS population. Because of this lack of long-term data, in some cases, therapy is currently initiated with the older, safer injectable medications, but patients are monitored closely with the plan to switch therapies if there is any indication of a suboptimal response or intolerance or lack of adherence to the initial therapy. For patients with MS who present with highly inflammatory and potentially aggressive disease, the benefit-to-risk ratio may support initiating therapy using a drug with greater potential efficacy despite greater risks (e.g. fingolimod or natalizumab if JC virus antibody-negative). The aim of this review is to discuss the clinical benefits, mechanisms of action, safety profiles and monitoring strategies of current MS disease-modifying therapies in clinical practice and of those expected to enter the market in the near future.

Role of galactosylceramide and sulfatide in oligodendrocytes and CNS myelin: formation of a glycosynapse

The two major glycosphingolipids of myelin, galactosylceramide (GalC) and sulfatide (SGC), interact with each other by trans carbohydrate-carbohydrate interactions in vitro. They face each other in the apposed extracellular surfaces of the multilayered myelin sheath produced by oligodendrocytes and could also contact each other between apposed oligodendrocyte processes. Multivalent galactose and sulfated galactose, in the form of GalC/SGC-containing liposomes or silica nanoparticles conjugated to galactose and galactose-3-sulfate, interact with GalC and SGC in the membrane sheets of oligodendrocytes in culture. This interaction causes transmembrane signaling, loss of the cytoskeleton and clustering of membrane domains, similar to the effects of cross-linking by anti-GalC and anti-SGC antibodies. These effects suggest that GalC and SGC could participate in glycosynapses, similar to neural synapses or the immunological synapse, between GSL-enriched membrane domains in apposed oligodendrocyte membranes or extracellular surfaces of mature myelin. Formation of such glycosynapses in vivo would be important for myelination and/or oligodendrocyte/myelin function.