metallothionein and Multiple-Sclerosis--Relapsing-Remitting

The choroid plexus (CP) is a key regulator of the central nervous system (CNS) homeostasis through its secretory, immunological and barrier properties. Accumulating evidence suggests that the CP plays a pivotal role in the pathogenesis of multiple sclerosis (MS), but the underlying mechanisms remain largely elusive. To get a comprehensive view on the role of the CP in MS, we studied transcriptomic alterations of the human CP in progressive MS and non-neurological disease controls using RNA sequencing. We identified 17 genes with significantly higher expression in progressive MS patients relative to that in controls. Among them is the newly described long non-coding RNA HIF1A-AS3. Next to that, we uncovered disease-affected pathways related to hypoxia, secretion and neuroprotection, while only subtle immunological and no barrier alterations were observed. In an ex vivo CP explant model, a subset of the upregulated genes responded in a similar way to hypoxic conditions. Our results suggest a deregulation of the Hypoxia-Inducible Factor (HIF)-1 pathway in progressive MS CP. Importantly, cerebrospinal fluid levels of the hypoxia-responsive secreted peptide PAI-1 were higher in MS patients with high disability relative to those with low disability. These findings provide for the first time a complete overview of the CP transcriptome in health and disease, and suggest that the CP environment becomes hypoxic in progressive MS patients, highlighting the altered secretory and neuroprotective properties of the CP under neuropathological conditions. Together, these findings provide novel insights to target the CP and promote the secretion of neuroprotective factors into the CNS of progressive MS patients.

Topics: Adrenomedullin; Adult; Aged; Case-Control Studies; Choroid Plexus; Female; Gene Expression Profiling; Gene Ontology; Glycoproteins; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Intercellular Signaling Peptides and Proteins; Lateral Ventricles; Male; Metallothionein; Middle Aged; Multiple Sclerosis, Chronic Progressive; Multiple Sclerosis, Relapsing-Remitting; Neuroprotection; Neurosecretion; Plasminogen Activator Inhibitor 1; RNA-Seq; RNA, Antisense; RNA, Long Noncoding

The importance of axonal damage in multiple sclerosis (MS) has been recently stressed in proton magnetic resonance spectroscopy and pathological studies, but the exact mechanism producing this damage is unknown. The aim of our study was to ascertain whether soluble mediators present in the cerebrospinal fluid (CSF) of patients with relapsing-remitting MS could induce neuron injury in culture. Different biochemical and cytochemical parameters were determined in primary embryonal rat neuron cultures following 8 days of exposure to CSF. Cytotoxic activity was evaluated with a blue formazan production colorimetric assay. Morphological and immunocytochemical studies performed with antibodies against beta-tubulin revealed neuritic fragmentation, axonal damage and cellular shrinkage indicating apoptosis. Detection of apoptosis was carried out using the fluorescent DNA-binding dye Hoechst 33342, as well as by a Terminal deoxynucleotidyl transferase-mediated dUTP Nick End-Labeling assay. We observed that soluble factors in CSF from patients with "aggressive" MS i.e, those with poor recovery after relapses, induced neurite breakdown and neuronal apoptosis in cultures. Neuron injury is not related with blood-brain barrier dysfunction nor with IgG index. Interestingly, CSF from patients with "non-aggressive" MS i.e., relapsing-remitting patients with a good recovery after relapses, did not induce any damage. In conclusion, we report that CSF from patients with aggressive MS bears soluble mediators that induce axonal damage and apoptosis of neurons in culture. These mediators can be present during the first attack of the disease, and the neuronal damage caused could be related to the functional deficit of these MS patients.

Topics: Adolescent; Adult; Animals; Apoptosis; Axons; Cells, Cultured; Cerebrospinal Fluid; Coloring Agents; Humans; Metallothionein; Microscopy, Confocal; Middle Aged; Multiple Sclerosis; Multiple Sclerosis, Relapsing-Remitting; Neurons; Rats; Tetrazolium Salts; Thiazoles