Treg-related immune suppression theory for ME/CFS and the use of very low dose cyclophosphamide

nandixon

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I have an idea for a different mechanism for immune dysfunction in ME/CFS to what Drs. Fluge and Mella suggest in their recent paper:

B-Lymphocyte Depletion in Myalgic Encephalopathy/ Chronic Fatigue Syndrome. An Open-Label Phase II Study with Rituximab Maintenance Treatment [2015]

and as a result, also a suggestion to investigate the possibility of using very low dose cyclophosphamide (CTX) as potentially an equally effective treatment to what those doctors have seen so far with both rituximab (RTX) and "normal" (i.e., high) dose CTX infusions, and with greater safety than standard oral dosing of CTX.

The authors state in the paper:
The lag time before clinical improvement may be compatible with a mechanism involving reduction of long-lived autoantibodies [Option 1], or some other slow alteration in immune function governed by B-cells [Option 2].
(My bracketed italics.)

If I understand correctly, Drs. Fluge and Mella have more recently found that CTX gives a much more rapid response than RTX. I think this tends to argue away somewhat from an autoimmune hypothesis (Option 1), although it doesn't rule it out by any means. One reason is that CTX is even less likely than RTX to affect the long-lived plasma cells responsible for the presumed lingering autoantibody production after RTX treatment.

Instead, I think it's possible that a reduction in pathological regulatory T cell (Treg) activity (an Option 2 possibility) could be behind the favorable response seen with both RTX and CTX. This would tend to make some variant of immune suppression more likely as a potential underlying cause of ME/CFS as opposed to autoimmunity.

(There's also the possibility for a sort of hybrid of Options 1 and 2, for example an agonistic autoantibody that increases Treg activity via a Treg cell receptor.)

If I understand correctly, depending on the background of the disease being treated, RTX has a sort of "dual" ability to potentially either reduce Tregs where a state of immune suppression is present (e.g., cancer), or to increase Tregs where there is autoimmunity. (It's not quite so simple but that's the general pattern, I think.)

CTX has the ability to "target" and destroy Tregs. (At normal/high doses it somewhat indiscriminately destroys other cell types as well.) And, as I've mentioned before in the rituximab forum, CTX can do this targeting of Tregs very selectively and at a much lower dose than is commonly used. This is because Tregs lack the p-glycoprotein (ABCB1) transporter capability that clears drugs like CTX from within cells. (See: Human regulatory T cells lack the cyclophosphamide-extruding transporter ABCB1 and are more susceptible to cyclophosphamide-induced apoptosis [2014])

I've been having continuous good success, for a month now, using cimetidine (Tagamet). It's the only substance I've found in 17+ years of having ME/CFS that has been able to partially reverse the disease (although not a cure by any means). (See, e.g., this post.)

Cimetidine is more commonly known as an older stomach acid reducer (an H2 blocker), but its most interesting ability, known to researchers since at least 1980, is its ability to decrease Treg activity in immune suppression states, particularly cancer. (Neither ranitidine nor famotidine affect my ME/CFS, ruling out a general H2 blocker or mast cell-related effect.)

I'm very suspicious that cimetidine is essentially acting as a "weaker" version of CTX. Cimetidine decreases Treg activity (possibly by interfering with an H2 receptor on the cell surface), while CTX actually destroys the Tregs and decreases their number.

I think it is worth investigating whether similar results to what have been seen so far using either RTX or normal (i.e., high) dose CTX infusions in the Norwegian trials can instead be achieved by using what I would term "very low dose cyclophosphamide" - in order to take advantage of the remarkable selectivity CTX has against Tregs at low concentrations (again, because Tregs lack ABCB1 gene expression and therefore lack the drug-clearing p-glycoprotein transporter).

This would be an amount of CTX certainly less than 50 mg (total) per day, given orally. For example, in theory I think 5 or 10 mg (or even less) a day is possibly a sufficient/effective amount for targeting only Tregs. I think that should be significantly safer in terms of potential bladder toxicity compared to standard oral dosing of CTX (e.g., >100 mg/day) and far less expensive than either RTX or the "normal" (i.e., high) dose infusions of CTX currently being studied in Norway. [Note: I'm a former medicinal chemist researcher, not a doctor. Do not try this at home!]

(The greater chance may be that the true problem lies upstream of the Tregs but is significantly impacting them, rather than there being an inherent problem with the Tregs themselves. So if for example the upstream problem lay with dysfunctional B cells, then in that case RTX might be a better choice for the long term than CTX - if RTX was actually capable of achieving a permanent or very sustained remission.)

Interestingly, significant Treg involvement in ME/CFS seems to also fit well with some of the endothelial- and nitric oxide-related observations that the Norwegians have made. See for example:

Self-recognition of the endothelium enables regulatory T-cell trafficking and defines the kinetics of immune regulation [2014]

Nitric Oxide Modulates TGF-β–Directive Signals To Suppress Foxp3+ Regulatory T Cell Differentiation and Potentiate Th1 Development [2011]

Myelin Basic Protein Priming Reduces the Expression of Foxp3 in T Cells via Nitric Oxide [2010]

Lastly, my understanding appears different with respect to a few points the authors note in the paper, as follows. They state:
Several studies have provided data suggesting autoimmunity as a possible mechanism in a subgroup of ME/CFS. Altered B-cell subtypes compared to healthy controls have been detected [31], also reduced NK-cell activity and elevated T-regulatory cells [32].
My understanding is that elevated Tregs are actually more generally associated with immune suppression, not autoimmunity. And that more typically, decreased numbers/activity of Tregs are found in autoimmune states.

The authors additionally state:
However, other underlying mechanisms than autoimmunity may explain the observed clinical effects of B-cell depletion on ME/CFS symptom maintenance. RTX influences other aspects of immune function than the pronounced effect on CD20 positive B-cells. These include... T-cell polarization to a suppressive phenotype...
Again, my understanding is that polarization towards a suppressive phenotype (i.e., increased Treg numbers/activity) tends to be the effect RTX has when it's used in autoimmune cases. I think the opposite (i.e., decreased Tregs) tends to occur when RTX is used in immune suppressed states.

In conclusion, I think an immune suppression state due to pathological Treg activity is a valid alternative explanation to the autoimmune possibility. This would also be more consistent with the yet to be published findings Dr. Jose Montoya of Stanford has mentioned regarding the very close similarity between ME/CFS and Systemic Inflammatory Response Syndrome (SIRS) found in a large gene expression study. (See, e.g., this post.)

Additionally, I believe that very low dose CTX might be useful to determine the extent of Treg involvement in ME/CFS - due to its capability to target Tregs in a highly selective manner - and if we were very lucky might possibly make a far less expensive treatment available sooner to a greater number of patients. To be clear, this is just a hypothetical possibility to explore.
 
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Mary

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@nandixon - this sounds interesting, but I have to admit that my brain starts to spin when attempting to read very technical things, though I think I got the gist of it. It's intriguing. I am wondering to whom (or what) you could submit your ideas for consideration.

Re the cimetidine - several years ago my doctor recommended I try it for my poor beleaguered immune system which has such a rough time fighting bugs, but it made me depressed, gave me a very dark mood which I read unfortunately was a side effect, so I had to stop it. But I am very glad it's helping you!
 

nandixon

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@Kati

I'm thinking in terms of 5-10 mg per day of cyclophosphamide (possibly less). This is no more than 1/10 of what would already be considered a low dose regimen (i.e., 50-100 mg/day). I wouldn't expect much risk of bladder toxicity at that very low level.

ETA: And the reference I cited in my original post suggests the possibility that closer to 1/100 dosing might not be out of the question:
In vitro, the ABCB1-substrate CPA [cyclophosphamide] was cytotoxic for Treg cells at a 100-fold lower dose than for nonregulatory counterparts...
 
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adreno

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Interesting, @nandixon.

As always, I suspect subtypes. Personally, I feel my disease is leaning more towards the autoimmune side. I have allergies, as well as POTS, which has recently been found to involve autoantibodies.

Recently, I've found that the probiotic Miyarisan (clostridium butyricum), which increases Tregs, have made significant improvements to my health.

Regarding NO, I've noticed that compounds that increase this seems to make me overall worse, whereas compounds that decrease NO seems to overall improve my symptoms.
 

msf

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But would Ritux cause a 'slow alteration' in the number of Tregs? For this theory to make sense, Ritux must kill them off slowly, and Cyclo must kill them off quickly, right? Unless you are suggesting that Ritux has no effect on them, and that its effect derives from Option 1.
 

nandixon

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But would Ritux cause a 'slow alteration' in the number of Tregs? For this theory to make sense, Ritux must kill them off slowly, and Cyclo must kill them off quickly, right? Unless you are suggesting that Ritux has no effect on them, and that its effect derives from Option 1.
Good question. My understanding is that there are long-lived Tregs that have the same sort of life span, i.e., months, that the long-lived plasma cells have that might be producing autoantibodies.

So once the "bad" B cells have been (rapidly) depleted by rituximab, whether they're bad because they're ultimately leading to plasma cell autoantibody production, or bad because they're leading to increased Treg activity and causing excessive immunosuppression, the time frame is approximately the same for the dying off of either the affected plasma cells or the affected Tregs, as the case may be.
 

nandixon

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Interesting, @nandixon.

As always, I suspect subtypes. Personally, I feel my disease is leaning more towards the autoimmune side.
Yes, it's very interesting the possibility that rituximab may be having such a high success rate (i.e., ~2/3) in ME/CFS because it's potentially capable of treating immune dysfunction at somewhat opposite ends of the spectrum.

So rather than seeing a 2/3 response rate due to those patients having the same immune dysfunction, and a 1/3 nonresponse rate, instead it might be the case, for example, that 1/3 respond and have a variation of autoimmunity, another 1/3 respond and have a variation of immune suppression, and 1/3 don't respond for whatever reason.
 

msf

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I don't know enough about this - do B cells affect Tregs? Over to you, Prof. Edwards...
 

Sidereal

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A few people on PR have reported major improvements on cimetidine scattered over various threads. Dr Goldstein reported in an anecdotal fashion many years ago that this drug worked well for a proportion of his patients. It amazes me that no one's done a trial since elevated Tregs and TGF-beta are measured so frequently in ME/CFS patients. You could do this with no funding since the drug is cheap and available OTC. I suspect it would only work for a minority since it doesn't address the underlying issue causing excessive immune suppression/tolerance observed in long-term ME.
 

deleder2k

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Very interesting. I would advise you to e-mail your hypothesis to the researchers in Bergen. I am sure they will find it interesting.

Contacts
Contact: Olav Mella, MD, PhD +47 55972069 olav.mella at helse-bergen dot no
Contact: Øystein Fluge, MD, PhD +47 55973587 oystein.fluge at helse-bergen dot no
 
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I don't know enough about this - do B cells affect Tregs? Over to you, Prof. Edwards...
I am sceptical about bringing in Tregs. The quick effect of cyclophosphamide would fit very well with the fact that rituximab doe snot kill plasma cells at all - you have to wait for them to die, but cyclophosphamide does have some cytotoxic effect - and it is the short lived plasma cells that are most relevant in autoimmunity we think.

I am not aware of any good reason to think Tregs are very important in autoimmunity. I know there is a lot of talk about it but mostly the animal evidence relates to autoinflammatory disease and it is unclear what specific mechanisms would be involved in human autoimmunity. On the other hand contributory B cell mechanisms are well understood.

I am not aware that B cell numbers have any consistent effect on Tregs or that rituximab has any consistent effect on T regs. There are likely to be some compensatory effects in Tregs with any treatment that improves a disease through other means so unless one can see why Treg changes should be relevant I would not put much significance on them even if they are found.

Daily oral cyclophosphamide is horribly toxic. Even 10mg a day long term I would not recommend. With the original dosages something like half of the people treated developed bladder cancer. Even a twenty fold less risk (2%) I would see as unacceptable.
 

Marky90

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I am sceptical about bringing in Tregs. The quick effect of cyclophosphamide would fit very well with the fact that rituximab doe snot kill plasma cells at all - you have to wait for them to die, but cyclophosphamide does have some cytotoxic effect - and it is the short lived plasma cells that are most relevant in autoimmunity we think.

I am not aware of any good reason to think Tregs are very important in autoimmunity. I know there is a lot of talk about it but mostly the animal evidence relates to autoinflammatory disease and it is unclear what specific mechanisms would be involved in human autoimmunity. On the other hand contributory B cell mechanisms are well understood.

I am not aware that B cell numbers have any consistent effect on Tregs or that rituximab has any consistent effect on T regs. There are likely to be some compensatory effects in Tregs with any treatment that improves a disease through other means so unless one can see why Treg changes should be relevant I would not put much significance on them even if they are found.

Daily oral cyclophosphamide is horribly toxic. Even 10mg a day long term I would not recommend. With the original dosages something like half of the people treated developed bladder cancer. Even a twenty fold less risk (2%) I would see as unacceptable.
Is it possible to explain for the layman, why short lived plasma cells are hypophesised to be the main culprits, and not the long lived ones?
 

nandixon

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Good question. My understanding is that there are long-lived Tregs that have the same sort of life span, i.e., months, that the long-lived plasma cells have that might be producing autoantibodies...
Speaking of plasma cells, in my post above where I said "long-lived plasma cells" that should have been "short-lived plasma cells."

ETA: I also made a similar mistake in the very first post of this thread.
 
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Is it possible to explain for the layman, why short lived plasma cells are hypophesised to be the main culprits, and not the long lived ones?
If you give rituximab many sorts of autoantibodies disappear gradually over about 3-6 months - showing what one might call an exponential wash out curve, consistent with gradual dying off of the cells that make them. On the other hand most antibodies to bacteria and viruses stay pretty constant even if the person's B cells do not come back for 4-5 years. That suggests that autoantibodies are produced by short lived plasma cells and that most antimicrobial antibodies are made by long lived plasma cells. The reason for this is probably that when there is an active immune response both short and long lived plasma cells are normally made. Long lived plasma cells may require some extra checking before they are allowed to settle in bone marrow. With an infection the short lived plasma cells disappear after 6 months just leaving long lived ones making antibody. With autoimmunity the active immune response keeps going all the time so short lived plasma cells keep being made. And maybe long lived plasma cells are mostly forbidden from going off to bone marrow, although some long-lived autoantibody remains even years after rituximab so there must be some of these present.
 

sillysocks84

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Recently, I've found that the probiotic Miyarisan (clostridium butyricum), which increases Tregs, have made significant improvements to my health.
Yes, I think increasing tregs for me would be good as well. I am having mast cell issues. I can find the link, but there was a very recent article how by "switching" tregs on in Mast cells can eliminate allergy reactions. So for people with pots and mast cells reaction perhaps we need to be looking into activating tregs
 

snowathlete

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If you give rituximab many sorts of autoantibodies disappear gradually over about 3-6 months - showing what one might call an exponential wash out curve, consistent with gradual dying off of the cells that make them. On the other hand most antibodies to bacteria and viruses stay pretty constant even if the person's B cells do not come back for 4-5 years. That suggests that autoantibodies are produced by short lived plasma cells and that most antimicrobial antibodies are made by long lived plasma cells. The reason for this is probably that when there is an active immune response both short and long lived plasma cells are normally made. Long lived plasma cells may require some extra checking before they are allowed to settle in bone marrow. With an infection the short lived plasma cells disappear after 6 months just leaving long lived ones making antibody. With autoimmunity the active immune response keeps going all the time so short lived plasma cells keep being made. And maybe long lived plasma cells are mostly forbidden from going off to bone marrow, although some long-lived autoantibody remains even years after rituximab so there must be some of these present.
Thanks for that explanation, it is really interesting. Are plasma cells born short- or long-lived, or can their life span set later? Perhaps with short-lived plasma cells able to become long-lived?
 
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Thanks for that explanation, it is really interesting. Are plasma cells born short- or long-lived, or can their life span set later? Perhaps with short-lived plasma cells able to become long-lived?
I am not sure we know too much about that. It seems likely that it is partly chance - plasma cells compete for space in bone marrow and the ones that do not find a space die - sort of musical chairs. But also it seems that some plasma cells are happy to go to spleen and live there for a short time. The behaviour of these cells seems to depend on surface receptors/ligands that may include things like CD38 and CD138 but also more recently discovered molecules I have forgotten the names of. In general we tend to see a spectrum of levels of expression of each of these ligands on a statistical basis (i.e. variation with roughly normal distribution). So for any given B cell clone expansion there will be a spectrum of plasma cells produced with different proclivities. It looks as if for autoreactive B cells the mean expression of certain ligands tends to shift the population to a shorter life span on average.
 

Ema

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Yes, I think increasing tregs for me would be good as well. I am having mast cell issues. I can find the link, but there was a very recent article how by "switching" tregs on in Mast cells can eliminate allergy reactions. So for people with pots and mast cells reaction perhaps we need to be looking into activating tregs
Interesting link on Tregs.
http://selfhacked.com/2014/11/11/treg/