Broad Analysis of Serum and Intrathecal Antimicrobial Antibodies in Multiple Sclerosis Underscores Unique Role of EBV, 2025, Florence Pache et al

Abstract
Background and Objectives
There is a strong link between Epstein-Barr virus (EBV) and multiple sclerosis (MS), but the underlying mechanisms are unclear. Patients with MS typically have a polyspecific intrathecal production of immunoglobulin G (IgG), part of which is directed against various microbial antigens. In this study, we comprehensively analyzed seroprevalences and frequencies of an intrathecal IgG production to EBV compared with 10 other common microbes in patients with MS.
Methods
Antibodies to EBV and to Borrelia burgdorferi, cytomegalovirus, herpes simplex virus type 1/2, measles virus, mumps virus, rubella virus, parvovirus B19, tick-borne encephalitis virus, Toxoplasma gondii, and varicella zoster virus (VZV) were determined in stored paired CSF and serum samples of 50 patients with MS. Intrathecal antimicrobial antibody production was assessed by calculating antibody indices (AIs) according to standard formula.
Results
While 50 (100%) of 50 patients with MS were EBV seropositive, seroprevalences of all other 10 microbes were lower, ranging from 94% (VZV) to 6% (Borrelia burgdorferi). An intrathecal production of antimicrobial antibodies was detected in 102 (28%) of 370 AI determinations of patients who were seropositive to the respective antimicrobial antibodies but was practically absent in seronegative patients (2/187 [1%], p < 0.0001). The frequency of intrathecally produced antimicrobial antibodies among patients who were seropositive for the respective antibodies was roughly 40% for measles, rubella, mumps, and VZV and 70% for parvovirus B19. By contrast, the frequency of intrathecally produced EBV antibodies was low (10%) and, when related to their respective seroprevalences, lower than those of all other investigated microbes.
Discussion
Despite the universal EBV seroprevalence, the frequency of intrathecally produced EBV antibodies in patients with MS is lower than that of other microbes, whose seroprevalences are lower than those of EBV. This seemingly paradoxical finding underscores the unique role of EBV in MS and could be explained by the hypothesis that B lineage cells responsible for intrathecal antibody production are primed during and through acute EBV infection to enter the CNS of patients with MS, that is, at a time point when EBV antibody-producing cells have not yet been generated and, therefore, are not yet available for entering the CNS.

LINK

 

I was having a tough time following what this says so I gave the abstract to an AI to put more simply:

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Background:

• There's a known connection between Epstein-Barr virus (EBV) and multiple sclerosis (MS), but scientists don't fully understand how they're linked
• MS patients typically produce antibodies in their nervous system against various microbes (like viruses and bacteria)

The Study:

• Researchers looked at 50 MS patients
• They tested for antibodies against EBV and 10 other common microbes in both blood and spinal fluid

Key Findings:

1. All MS patients (100%) had EBV antibodies in their blood
2. Fewer patients had antibodies to the other microbes in their blood
3. When looking at antibodies produced in the spinal fluid:
   • Only 10% of patients made EBV antibodies there
   • About 40-70% made antibodies against other microbes there

The Interesting Part: This seems odd - even though everyone had EBV antibodies in their blood, very few had them in their spinal fluid. The researchers think this might be because EBV infection happens before MS develops, and by the time MS starts, the body isn't actively making new EBV antibodies anymore.

This supports the idea that EBV plays a special role in MS, different from other infections.

 

Is it just that the B cells that enter CSF upon EBV infection already produce antibodies to pathogens seen before the EBV infection?

 

This finding is very interesting and very consistent with the way I have always looked at MS - not as a cross-reactive disease but as a failure of the normal general barrier to B cell entry to CNS.

EBV could have been relevant to MS because of B cells recognising EBV but this study gives the opposite result to what would be expected for that.

What was always more plausible to me is that EBV simply does what we know it does - it overrides the normal control of B cell survival generally such that B cells can make antibodies or go places normally forbidden. If you want to make a B cell survive and proliferate in the lab without proper 'approval signals' from other cells you feed it EBV. So-called ebb-transformed cells become almost neoplastic.

So the idea is that during EBV infection you have a period during which early B cells are allowed to progress to memory B cells and set up home in lymph node and spleen even though they are a bit 'dodgy' or 'naughty' in terms of making antibody species that give them dangerous properties. It doesn't matter a hoot what microbes they recognise, the problem is that the can 'play out of school' under certain conditions.

And the obvious thing that B cells do wrong in MS is that they climb in to the brain when they have no business there. B cells are not inflammation cells. They are, as I have said before, like trainee lawyers who are supposed only to live in the law school of lymph node follicles and learn what laws they are supposed to write and which not, when one day they turn in to plasma cells and are sent to bone marrow law courts where they flood the bloodstream with judgments in the form of antibodies.

In MS it seems the law students climb into the brain for reasons we don't know but which do not seem to have anything to do with microbes being in the brain. There aren't any microbes of any particular sort in the brain and the B cells don't make antibodies to any particular sort. The obvious option is that these are B cells whose surface antibodies just happen to stick to brain cell endothelium. That may have nothing to do with specific affinities. It might be due to an amino acid in the protein sequence that distorts the binding site in some non-specific way that makes it stick more. It might even be that EBV-expanded B cells get a bit large (they do) and jam in the brain capillaries and then wander into brain.

There is another factor to add in to this. Although it seems that B cells are not normally allowed in to brain it may also be that once inside brain B cells find it easier to survive because there are no killer CD57 T cells there and the need for survival support ligands (?bcl2, bclx, I forget) is less. And that of course may be a reason why the brain has to exclude them.

There are some awkward questions about any more detailed model. The evidence suggests to some extent that the B cells making antibody in brain are from the same lines as at the start for each relapse in a new part of the brain. But there can also be new lines appearing with new relapses. Moreover, the lines might be the same because new relapses just allow a form more of the same dodgy lines into brain. Rituximab doesn't get into brain but it prevents new relapses. That suggests that new relapses are due to more B cells from blood getting in to brain.

There is a lot more to the story. Jo Cambridge and I have talked it over for hours over decades. But this to me makes complete sense. EBV makes B cells generally go AWOL. Nothing to do with any microbes or infections in brain or cross reactivities or even EBV B cells. Most EBV expanded B cells are not EBV specific and so this is no surprise.

 

Pretty much although it may be a bit more complicated.

 

Thanks, that's fascinating. I didn't know the story about B cells being able to travel without tickets after EBV exposure.

 

So it sounds like the problem in MS is mainly B cells in the brain, so do you know if there are promising methods to get them out?

Can you maybe inject something into the brain that sticks to B cells and makes brain immune cells more likely to grab them? (I don't really know much about how the brain immune system works.)

 

Or maybe stop more going in. Rituximab probably does that and if you gave it often enough to keep B cells out of the blood you might prevent any further episodes. The problem is with the fall in immunoglobulin levels and lack of antibody response to infection.

The hard question is why there continue to be errant B cells ready to go into the brain and why if you stop rituximab they go in again. There is something important we do not understand about the long term failure of control. CAR-T depletion of B cells might do the trick.

Interestingly you can clear someone of EBV with drugs like rituximab - it is useful for EBV-reactivation in immunosuppressed patients.

Trying to clear cells from brain is likely to be hard although you could use drugs infused into CSF. The problem is that if more go in later you have not solved the problem.

The sad thing is that people working on these diseases have so little grasp of the complicated system dynamics. The drug companies are no interested in cures. They want expensive long term maintenance protocols to make a big profit.

 

Ah, I thought the thread's paper was showing that they pretty much only enter during the acute EBV infection and then stick around forever, because if new B cells are going in, there'd be many more antibodies to EBV in the CSF.

 

Interestingly, there is another possible explanation - that a B cell committed to making antibodies to EBV cannot support its own EBV infection (because it would be full of anti-EBV antibody). So EBV could expand clones recognising other microbes but not EBV. The anti-EBV clones would go on behaving normally and not go into brain.

I am sceptical that all the B cells go in at the beginning. If that were so rituximab should have no effect on blocking relapses since it does not get into the brain.

 

I think this is the Post-Covid PASC study but still interesting.
We have no evidence of focal demyelination lesions like MS in ME/CFS or PASC so it seems unlikely that B cells are getting in to brain through brain parenchyma. However, maybe it is possible for something analogous to occur across meningeal or choroid vessels so that B cells get into CSF without damaging brain on the way. The symptoms might be more similar to meningism with intolerance of stimuli like light.

The plot from the Nath paper might reflect an artefact of controls being historic though. I wonder if the cells had been frozen. B cells are not good at making antibody unless given strong encouragement with something like EBV or PMA and they tend to sulk and die in vitro most of the time. Freezing could well be a big problem. But maybe the cells had been studied fresh previously?

 

Note that to get MS you pretty much have to have certain genetic variant risk factors. That might mean that AWOL B cells can only colonise brain in a tiny proportion of people whether or not infected with EBV. That means that for the other 95% of us the only way B cells could get into CNS might be through meningeal vessels. Since Covid seems to produce neurological complications in some maybe one of the features of the virus is to allow B cells to cross vessels more generally. In all other tissue they will just drop dead because the tissues have T cell surveillance. But for meninges and brain that surveillance isn' there.

It is conceivable that this is relevant to ME/CFS too. It might actually make sense of the accounts of post-mortem dorsal root ganglionitis.
It would also be consistent with benefit from cyclophosphamide but not rituximab.

 

Would dorsal root ganglionitis only be observable on post mortem or could it be detected by scans? Quite a few PwME have probably had spinal MRI scans.

 

It might be quite hard to detect. If the inflammation consisted only of diffuse lymphocyte infiltration without oedema MRI might not show much. If symptoms were caused by antibodies in the CSF rather than the ganglionitis itself - which might just be a bystander effect - then there might be severe symptoms without enough structural change to show on a scan.

 

The UK ME/CFS Biobank only seems to have blood in it, but last October, the MEA announced that they were funding a new post-mortem tissue research programme at the Manchester Brain Bank.

They said: 'The MEA Ramsay Research Fund will be funding detailed examinations of the brain, spinal cord and dorsal root ganglion in at least 5 people with a firm diagnosis ME/CFS who are aged between 18 and 50 at the time of death. We will then review the results and decide whether to proceed with funding further examinations.'

Does this mean that the research you would want to examine this idea is already under way?

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