Where do you look for important cells in MS? A few months ago we were led to believe that CD8 T cells were important.
Sabatino JJ Jr, Wilson MR, Calabresi PA, Hauser SL, Schneck JP, Zamvil SS.Proc Natl Acad Sci U S A. 2019 Dec 17;116(51):25800-25807
Today we are back on the B cell trail notably the memory B cells trail.
A pathogenic and clonally expanded B cell transcriptome in active multiple sclerosis.Ramesh A, Schubert RD, Greenfield AL, Dandekar R, Loudermilk R, Sabatino JJ Jr, Koelzer MT, Tran EB, Koshal K, Kim K, Pröbstel AK, Banerji D; University of California, San Francisco MS-EPIC Team, Guo CY, Green AJ, Bove RM, DeRisi JL, Gelfand JM, Cree BAC, Zamvil SS, Baranzini SE, Hauser SL, Wilson MR.Proc Natl Acad Sci U S A. 2020 Aug 28:202008523. doi: 10.1073/pnas.2008523117.
B cells serve as a key weapon against infectious diseases. They also contribute to multiple autoimmune diseases, including multiple sclerosis (MS) where depletion of B cells is a highly effective therapy. We describe a comprehensive profile of central nervous system (CNS)-specific transcriptional B cell phenotypes in MS at single-cell resolution with paired immune repertoires. We reveal a polyclonal immunoglobulin M (IgM) and IgG1 cerebrospinal fluid B cell expansion polarized toward an inflammatory, memory and plasmablast/plasma cell phenotype, with differential up-regulation of specific proinflammatory pathways. We did not find evidence that CNS B cells harbor a neurotropic virus. These data support the targeting of activated resident B cells in the CNS as a potentially effective strategy for control of treatment-resistant chronic disease.
Substantial B cell clonal expansion was observed in the CSF of patients with RRMS. In contrast, clonal expansion was not detected in the CSF of the health controls. CSF B cell clonal expansion was linked to the presence of unique oligoclonal bands in RRMS and identified clonal expansion primarily in the memory and plasmablast/plasma cell compartments
In MS patients, the CSF has a remarkably different cellular profile from the blood. Very few B cells in healthy CSF. In addition, they found an expansion of CD4+ and CD8+ T cells in the CSF. The CSF also contained a relative dearth of NK cells compared with the blood This suggests that ocrelizuamb may be a bit rubbish at depleting cells in the brain as you would expect NK cells are an cell type involved in the killling process of antibodies.
So they find expanded B cells but didnt find a virus at the core of this. I am not too concerned by this but it questions that they are targets for EBV specific T cells. I suspect that if their cellular-mothers were infected with EBV they don’t still have to be, as the importance could be that the EBV made the cell become a memory B cell and once this has happened it has happened. There was no evidence of HERVS (Human endogenous retro virus)
Central nervous system B cells have several potential roles in multiple sclerosis (MS): secretors of proinflammatory cytokines and chemokines, presenters of autoantigens to T cells, producers of pathogenic antibodies, and reservoirs for viruses that trigger demyelination. To interrogate these roles, single-cell RNA sequencing (scRNA-Seq) was performed on paired cerebrospinal fluid (CSF) and blood from subjects with relapsing-remitting MS (RRMS; n = 12), other neurologic diseases (ONDs; n = 1), and healthy controls (HCs; n = 3). Single-cell immunoglobulin sequencing (scIg-Seq) was performed on a subset of these subjects and additional RRMS (n = 4), clinically isolated syndrome (n = 2), and OND (n = 2) subjects (N=2 is too small to be meaning ful and is not worth reporting until more samples are analysed) . Further, paired CSF and blood B cell subsets (RRMS; n = 7) were isolated using fluorescence activated cell sorting for bulk RNA sequencing (RNA-Seq). Independent analyses across technologies demonstrated that nuclear factor kappa B (NF-κB) and cholesterol biosynthesis pathways were activated, and specific cytokine and chemokine receptors were up-regulated in CSF memory B cells. Further, SMAD/TGF-β1 signaling was down-regulated in CSF plasmablasts/plasma cells. Clonally expanded, somatically hypermutated IgM+ and IgG1+ CSF B cells were associated with inflammation, blood-brain barrier breakdown, and intrathecal Ig synthesis. While we identified memory B cells and plasmablast/plasma cells with highly similar Ig heavy-chain sequences across MS subjects, similarities were also identified with ONDs and HCs. No viral transcripts, including from Epstein-Barr virus, were detected. Our findings support the hypothesis that in MS, CSF B cells are driven to an inflammatory and clonally expanded memory and plasmablast/plasma cell phenotype.
The problem of this approach is you are selecting a type of cell thats is attrached into the central nervous system, but it may be recruited in because it has the right adhesion molecules and it does not mean it an essential pathogenic cell, so you are looking for the needle in the haystack and again says if you dont know where to look, you may be looking in the wrong place. However their are expanded B cells and with this approach you know the sequence of the antibody molecules, you can make them and the see what they react to. I am surethis will happen…and we will find they are…….. not really reactive with myelin basic protein and they will be against proteins inside cells.