Project description:Oligodendrocyte (OL) pathology is increasingly implicated in neurodegenerative diseases, as they are involved in metabolic support of axons and functional cross-talk with other brain cells. Rodent OLs are heterogeneous, with developmental and biological differences, but the extent of heterogeneity in the normal human brain and its contribution to any changes of disease remains unknown. Here we performed single nuclei RNA-sequencing (snRNA-seq) from white matter (WM) areas of post mortem human brain both in control (Ctr) and multiple sclerosis (MS) patients. We identified several sub-clusters of oligodendroglia in the Ctr human WM, some similar to those in mouse, and defined new markers for these. Strikingly, some of these sub-clusters were under-represented in MS tissue, while others were more prevalent than in controls. There was a lack of OL precursor cells (OPCs) and OLs in an intermediate stage of differentiation in MS lesions and in normal appearing white matter (NAWM), suggesting either depletion by the disease or by a regenerative response. The differences in mature OL sub-clusters indicate different functional states of OLs in MS tissue and, as this is similar in NAWM to lesions, that MS is a more diffuse brain disease than the focal demyelinating lesions suggest. We were also able to identify new markers of different MS lesion subtypes. Our findings of an altered heterogeneity of oligodendroglia in MS may have an important contribution to our understanding of disease progression and may alter therapeutic approaches to MS.
Project description:This study is currently hosted by the European Nucleotide Archive. To access the data contained within the Study please follow the link below:
https://www.ebi.ac.uk/ena/browser/view/PRJEB39323
Oligodendrocyte (OL) pathology is increasingly implicated in neurodegenerative diseases, as they are involved in metabolic support of axons and functional cross-talk with other brain cells. Rodent OLs are heterogeneous, with developmental and biological differences, but the extent of heterogeneity in the normal human brain and its contribution to any changes to disease remains unknown. Here we performed single nuclei RNA-sequencing (snRNA-seq) from white matter (WM) areas of post mortem human brain both in control (Ctr) and multiple sclerosis (MS) patients. We identified several sub-clusters of oligodendroglia in the Ctr human WM, some similar to those in mouse, and defined new markers for these cell states. Strikingly, some of these sub-clusters were under-represented in MS tissue, while others were more prevalent than in controls. We found a lack of OL precursor cells (OPCs) and an OL subcluster in an intermediate stage of differentiation in MS lesions and in normal appearing white matter (NAWM), suggesting either depletion by the disease or by a regenerative response. The differences in mature OL sub-clusters indicate different functional states of OLs in MS tissue and, as this is similar in NAWM to lesions, that MS is a more diffuse brain disease than the focal demyelinating lesions suggest. We were also able to identify new putative markers of different MS lesion subtypes. Our findings of an altered heterogeneity of oligodendroglia in MS may have an important contribution to our understanding of disease progression and may alter therapeutic approaches to MS.
Project description:This study provides an overview of the transcriptional signature of oligodendrocyte progenitor cells (OPCs) exposed to the CSF collected from multiple sclerosis patients with either a relapsing remitting disease course (RRMS) or a confirmed primary progressive diagnosis (PPMS). Using an Affymetrix microarray we were able to detect a set of common and unique genes for each treatment group. Gene ontology analysis revealed a common group of genes involved in protein transport, actin dynamics and response to stress and DNA damage, while the RRMS-specific genes were grouped according to protein complex biogenesis, nuclear transport and RNA processing. The transcriptional signature of progenitors exposed to PPMS was characterized by an up-regulation of the pro-differentiation adhesion molecule Lgals3. We confirmed increased protein levels of its gene product,product; galectin-3 in proliferating OPCs incubated with CSF from PPMS patients and also found a four-fold increase in mRNA transcript levels of galectin-3 in human post-mortem normal-appearing white matter samples of primary progressive MS patients when compared to non-neurological controls. This study will help to better understand the common and specific transcriptional changes induced in the different subtypes of MS and therefore find more specific molecular targets for each disease subtype. Comparison of transcriptional signature by microarray analysis of OPCs treated with RRMS and PPMS CSF.
Project description:Using the Illumina 450K array and a stringent statistical analysis with age and gender correction, we report genome-wide differences in DNA methylation between pathology-free regions derived from human multiple sclerosis–affected and control brains. Differences were subtle, but widespread and reproducible in an independent validation cohort. The transcriptional consequences of differential DNA methylation were further defined by genome-wide RNA-sequencing analysis and validated in two independent cohorts. Genes regulating oligodendrocyte survival, such as BCL2L2 and NDRG1, were hypermethylated and expressed at lower levels in multiple sclerosis–affected brains than in controls, while genes related to proteolytic processing (for example, LGMN, CTSZ) were hypomethylated and expressed at higher levels. These results were not due to differences in cellular composition between multiple sclerosis and controls. Thus, epigenomic changes in genes affecting oligodendrocyte susceptibility to damage are detected in pathology-free areas of multiple sclerosis–affected brains.