The elegance of metabolism control in the cell.

The current two pronged research effort on the possible use of Gemfibrozil (Lopid) to treat Alzheimer’s disease now has far wider implications than Alzheimer’s disease alone. As far as I’m aware, the combination of mechanisms described below to control a cellular pathway as never been reported before.

A previous post has the story up to 3 August — https://luysii.wordpress.com/2015/08/03/takes-me-right-back-to-grad-school/ — you can read it for the details, but here’s some background and the rest of the story.

Background: One of the two pathologic hallmarks of Alzheimer’s disease is the senile plaque (the other is the neurofibrillary tangle). The major component of the plaque is a fragment of a protein called APP (Amyloid Precursor Protein). Normally it sits in the cellular membrane of nerve cells (neurons) with part sticking outside the cell and another part sticking inside. The protein as made by the cell contains anywhere from 563 to 770 amino acids linked together in a long chain. The fragment destined to make up the senile plaque (called the Abeta peptide) is much smaller (39 to 42 amino acids) and is found in the parts of APP embedded in the membrane and sticking outside the cell.

No protein lives forever in the cell, and APP is no exception. There are a variety of ways to chop it up, so its amino acids can be used for other things. One such chopper is called ADAM10 (aka Kuzbanian). ADAM10breaks down APP in such a way that Abeta isn’t formed. A paper in the 7 July PNAS (vol. 112 pp. 8445 – 8450 ’15 7 July ’15) essentially found that Gemfibrozil (commercial name Lopid) increases the amount of ADAM10 around. If you take a mouse genetically modified so that it will get senile plaques and decrease ADAM10 you get a lot more plaques.

I wrote the author (Dr. Pahan) to ask how they came up with Gemfibrozil (Lopid). He told me that a transcription factor (PPARalpha) helps transcribe the ADAM10 gene into mRNA, and that Gemfibrozil makes PPARalpha a better transcription factor.

I told him to datamine from HMOs to find out if people on Lopid had less Alzheimer’s, he said it would be hard to get such as grant to do this as a basic researcher.

A commenter on the first post gave me a name to contact to try out the idea, but I’ve been unable to reach her. So on 3 August, I wrote an Alzheimer’s researcher at Yale about it. He responded nearly immediately with a link to an ongoing clinical study in progress in Kentucky, actually using Gemfibrozil.

Both researchers (Dr. Jicha and Nelson) were extremely helpful and cooperative. What is so fascinating is that they got to Gemfibrozil by an entirely different route. There are degrees of Alzheimer’s disease, and there is a pathologic grading scheme for it. They studied postmortem brain of 4 classes of individuals — normal nondemented elderly with minimal plaque, non demented elderly with incipient plaque, mild cognitive impairment and full flown Alzheimer’s. They had studied the microRNA #107 (miR-107) in another context. Why this one of the thousand or so microRNAs in the human genome? Because it binds to the mRNA of BACE1 and prevents it from being made. Why is this good? Because BACE1 chops up APP at a different site so the Abeta peptide is formed.

How did Gemfibrozil get into the act? Just as Dr. Pahan did, they looked to see what transcription factors were involved in making miR-107, and found PPARalpha. So to make less BACE1 they give people Gemfibrozil which turns on PPARalpha which turns on miR-107, which causes the mRNA for BACE1 to be destroyed, hopefully making less Abeta. The study is in progress and will last a year, far too short with far too few people to see a meaningful cognitive effect, but not so short that they won’t see changes in the biologic markers  they are studying in the spinal fluids (yes 72 plucky individuals have agreed to take Gemfibrozil (or not) and have two spinal taps one year apart.

The elegance of all this is simply astounding. A single transcription factor –PPARalpha  turns on a gene for a chopper — ADAM10 (aka Kuzbanian) which chops up APP so that the  toxic Abeta isoform is not made.  Amazingly, PPARalpha also turns on a microRNA (miR-107 ) which decreases the amount of a different APP chopper (BACE1) which produces toxic Abeta from APP, so that less toxic Abeta peptide is formed.

So there’s a whole research program for you. Take a given transcription factor, look at the protein genes it turns on. Then look at the microRNA genes it turns on and then see what protein mRNAs they turn off. Then see they affect the same biochemical pathway as do ADAM10 and BACE1.

The mechanism is so elegant (although hardly simple) that I’ll bet the cell uses it again, in completely different pathways.

One problem with PPARalpha is that it is said to affect HUNDREDS of genes (Mol. Metab vol. 3 pp. 354 371 ’14).  So Gemfibrozil is a nice story, but even if it works, we won’t really be sure it’s doing so by ADAM10 and microRNA-107.

Takes me right back to grad school

How many times in grad school did you or your friends come up with a good idea, only to see it appear in the literature a few months later by someone who’d been working on it for much longer. We’d console ourselves with the knowledge that at least we were thinking well and move on.

Exactly that happened to what I thought was an original idea in my last post — e.g. that Gemfibrozil (Lopid) might slow down (or even treat) Alzheimer’s disease. I considered the post the most significant one I’d ever written, and didn’t post anything else for a week or two, so anyone coming to the blog for any reason would see it first.

A commenter on the first post gave me a name to contact to try out the idea, but I’ve been unable to reach her. Derek Lowe was quite helpful in letting me link to the post, so presently the post has had over 200 hits. Today I wrote an Alzheimer’s researcher at Yale about it. He responded nearly immediately with a link to an ongoing clinical study in progress in Kentucky

On Aug 3, 2015, at 3:04 PM, Christopher van Dyck wrote:

Dear Dr. xxxxx

Thanks for your email. I agree that this is a promising mechanism.
My colleague Greg Jicha at U.Kentucky is already working on this:
https://www.nia.nih.gov/alzheimers/clinical-trials/gemfibrozil-predementia-alzheimers-disease

Our current efforts at Yale are on other mechanisms:
http://www.adcs.org/studies/Connect.aspx

We can’t all test every mechanism, but hopefully we can collectively test the important ones.

-best regards,
Christopher H. van Dyck, MD
Professor of Psychiatry, Neurology, and Neurobiology
Director, Alzheimers Disease Research Unit

Am I unhappy about losing fame and glory being the first to think of it?  Not in the slightest.  Alzheimer’s is a terrible disease and it’s great to see the idea being tested.

Even more interestingly, a look at the website for the study shows, that somehow they got to Gemfibrozil by a different mechanism — microRNAs rather than PPARalpha.

I plan to get in touch with Dr. Jicha to see how he found his way to Gemfibrozil. The study is only 1 year in duration, and hopefully is well enough powered to find an effect. These studies are incredibly expensive (and an excellent use of my taxes). I never been involved in anything like this, but data mining existing HMO data simply has to be cheaper. How much cheaper I don’t know.

Here’s the previous post —

Could Gemfibrozil (Lopid) be used to slow down (or even treat) Alzheimer’s disease?

Is a treatment of Alzheimer’s disease at hand with a drug in clinical use for nearly 40 years? A paper in this week’s PNAS implies that it might (vol. 112 pp. 8445 – 8450 ’15 7 July ’15). First a lot more background than I usually provide, because some family members of the afflicted read everything they can get their hands on, and few of them have medical or biochemical training. The cognoscenti can skip past this to the text marked ***

One of the two pathologic hallmarks of Alzheimer’s disease is the senile plaque (the other is the neurofibrillary tangle). The major component of the plaque is a fragment of a protein called APP (Amyloid Precursor Protein). Normally it sits in the cellular membrane of nerve cells (neurons) with part sticking outside the cell and another part sticking inside. The protein as made by the cell contains anywhere from 563 to 770 amino acids linked together in a long chain. The fragment destined to make up the senile plaque (called the Abeta peptide) is much smaller (39 to 42 amino acids) and is found in the parts of APP embedded in the membrane and sticking outside the cell.

No protein lives forever in the cell, and APP is no exception. There are a variety of ways to chop it up, so its amino acids can be used for other things. One such chopper is called ADAM10 (aka Kuzbanian). ADAM10breaks down APP in such a way that Abeta isn’t formed. The paper essentially found that Gemfibrozil (commercial name Lopid) increases the amount of ADAM10 around. If you take a mouse genetically modified so that it will get senile plaques and decrease ADAM10 you get a lot more plaques.

The authors didn’t artificially increase the amount of ADAM10 to see if the animals got fewer plaques (that’s probably their next paper).

So there you have it. Should your loved one get Gemfibrozil? It’s a very long shot and the drug has significant side effects. For just how long a shot and the chain of inferences why this is so look at the text marked @@@@

****

How does Gemfibrozil increase the amount of ADAM10 around? It binds to a protein called PPARalpha which is a type of nuclear hormone receptor. PPARalpha binds to another protein called RXR, and together they turn on the transcription of a variety of genes, most of which are related to lipid metabolism. One of the genes turned on is ADAM10, which really has never been mentioned in the context of lipid metabolism. In any event Gemfibrozil binds to PPARalpha which binds more effectively to RAR which binds more effectively to the promoter of the ADAM10 gene which makes more ADAM10 which chops of APP in such fashion that Abeta isn’t made.

How in the world the authors got to PPARalpha from ADAM10 is unknown — but I’ve written the following to the lead author just before writing this post.

Dr. Pahan;

Great paper. People have been focused on ADAM10 for years. It isn’t clear to me how you were led to PPARgamma from reading your paper. I’m not sure how many people are still on Gemfibrozil. Probably most of them have some form of vascular disease, which increases the risk of dementia of all sorts (including Alzheimer’s). Nonetheless large HMOs have prescription data which can be mined to see if the incidence of Alzheimer’s is less on Gemfibrozil than those taking other lipid lowering agents, or the population at large. One such example (involving another class of drugs) is JAMA Intern Med. 2015;175(3):401-407, where the prescriptions of 3,434 individuals 65 years or older in Group Health, an integrated health care delivery system in Seattle, Washington. I thought the conclusions were totally unwarranted, but it shows what can be done with data already out there. Did you look at other fibrates (such as Atromid)?

Update: 22 July ’15

I received the following back from the author

Dear Dr.

Wonderful suggestion. However, here, we have focused on the basic science part because the NIH supports basic science discovery. It is very difficult to compete for NIH R01 grants using data mining approach.

It is PPARα, but not PPARγ, that is involved in the regulation of ADAM10. We searched ADAM10 gene promoter and found a site where PPAR can bind. Then using knockout cells and ChIP assay, we confirmed the participation of PPARα, the protein that controls fatty acid metabolism in the liver, suggesting that plaque formation is controlled by a lipid-lowering protein. Therefore, many colleagues are sending kudos for this publication.

Thank you.

Kalipada Pahan, Ph.D.

The Floyd A. Davis, M.D., Endowed Chair of Neurology

Professor

Departments of Neurological Sciences, Biochemistry and Pharmacology

So there you have it. An idea worth pursuing according to Dr. Pahan, but one which he can’t (or won’t). So, dear reader, take it upon yourself (if you can) to mine the data on people given Gemfibrozil to see if their risk of Alzheimer’s is lower. I won’t stand in your way or compete with you as I’m a retired clinical neurologist with no academic affiliation. The data is certainly out there, just as it was for the JAMA Intern Med. 2015;175(3):401-407 study. Bon voyage.

@@@@

There are side effects, one of which is a severe muscle disease, and as a neurologist I saw someone so severely weakened by drugs of this class that they were on a respirator being too weak to breathe (they recovered). The use of Gemfibrozil rests on the assumption that the senile plaque and Abeta peptide are causative of Alzheimer’s. A huge amount of money has been spent and lost on drugs (antibodies mostly) trying to get rid of the plaques. None have helped clinically. It is possible that the plaque is the last gasp of a neuron dying of something else (e.g. a tombstone rather than a smoking gun). It is also possible that the plaque is actually a way the neuron was defending itself against what was trying to kill it (e.g. the plaque as a pile of spent bullets).

Could Gemfibrozil (Lopid) be used to slow down (or even treat) Alzheimer’s disease?

Is a treatment of Alzheimer’s disease at hand with a drug in clinical use for nearly 40 years? A paper in this week’s PNAS implies that it might (vol. 112 pp. 8445 – 8450 ’15 7 July ’15). First a lot more background than I usually provide, because some family members of the afflicted read everything they can get their hands on, and few of them have medical or biochemical training. The cognoscenti can skip past this to the text marked ***

One of the two pathologic hallmarks of Alzheimer’s disease is the senile plaque (the other is the neurofibrillary tangle). The major component of the plaque is a fragment of a protein called APP (Amyloid Precursor Protein). Normally it sits in the cellular membrane of nerve cells (neurons) with part sticking outside the cell and another part sticking inside. The protein as made by the cell contains anywhere from 563 to 770 amino acids linked together in a long chain. The fragment destined to make up the senile plaque (called the Abeta peptide) is much smaller (39 to 42 amino acids) and is found in the parts of APP embedded in the membrane and sticking outside the cell.

No protein lives forever in the cell, and APP is no exception. There are a variety of ways to chop it up, so its amino acids can be used for other things. One such chopper is called ADAM10 (aka Kuzbanian). ADAM10breaks down APP in such a way that Abeta isn’t formed. The paper essentially found that Gemfibrozil (commercial name Lopid) increases the amount of ADAM10 around. If you take a mouse genetically modified so that it will get senile plaques and decrease ADAM10 you get a lot more plaques.

The authors didn’t artificially increase the amount of ADAM10 to see if the animals got fewer plaques (that’s probably their next paper).

So there you have it. Should your loved one get Gemfibrozil? It’s a very long shot and the drug has significant side effects. For just how long a shot and the chain of inferences why this is so look at the text marked @@@@

****

How does Gemfibrozil increase the amount of ADAM10 around? It binds to a protein called PPARalpha which is a type of nuclear hormone receptor. PPARalpha binds to another protein called RXR, and together they turn on the transcription of a variety of genes, most of which are related to lipid metabolism. One of the genes turned on is ADAM10, which really has never been mentioned in the context of lipid metabolism. In any event Gemfibrozil binds to PPARalpha which binds more effectively to RAR which binds more effectively to the promoter of the ADAM10 gene which makes more ADAM10 which chops of APP in such fashion that Abeta isn’t made.

How in the world the authors got to PPARalpha from ADAM10 is unknown — but I’ve written the following to the lead author just before writing this post.

Dr. Pahan;

Great paper. People have been focused on ADAM10 for years. It isn’t clear to me how you were led to PPARgamma from reading your paper. I’m not sure how many people are still on Gemfibrozil. Probably most of them have some form of vascular disease, which increases the risk of dementia of all sorts (including Alzheimer’s). Nonetheless large HMOs have prescription data which can be mined to see if the incidence of Alzheimer’s is less on Gemfibrozil than those taking other lipid lowering agents, or the population at large. One such example (involving another class of drugs) is JAMA Intern Med. 2015;175(3):401-407, where the prescriptions of 3,434 individuals 65 years or older in Group Health, an integrated health care delivery system in Seattle, Washington. I thought the conclusions were totally unwarranted, but it shows what can be done with data already out there. Did you look at other fibrates (such as Atromid)?

Update: 22 July ’15

I received the following back from the author

Dear Dr.

Wonderful suggestion. However, here, we have focused on the basic science part because the NIH supports basic science discovery. It is very difficult to compete for NIH R01 grants using data mining approach.

It is PPARα, but not PPARγ, that is involved in the regulation of ADAM10. We searched ADAM10 gene promoter and found a site where PPAR can bind. Then using knockout cells and ChIP assay, we confirmed the participation of PPARα, the protein that controls fatty acid metabolism in the liver, suggesting that plaque formation is controlled by a lipid-lowering protein. Therefore, many colleagues are sending kudos for this publication.

Thank you.

Kalipada Pahan, Ph.D.

The Floyd A. Davis, M.D., Endowed Chair of Neurology

Professor

Departments of Neurological Sciences, Biochemistry and Pharmacology

So there you have it.  An idea worth pursuing according to Dr. Pahan, but one which he can’t (or won’t).  So, dear reader, take it upon yourself (if you can) to mine the data on people given Gemfibrozil to see if their risk of Alzheimer’s is lower.  I won’t stand in your way or compete with you as I’m a retired clinical neurologist with no academic affiliation. The data is certainly out there, just as it was for the JAMA Intern Med. 2015;175(3):401-407 study.  Bon voyage.

@@@@

There are side effects, one of which is a severe muscle disease, and as a neurologist I saw someone so severely weakened by drugs of this class that they were on a respirator being too weak to breathe (they recovered). The use of Gemfibrozil rests on the assumption that the senile plaque and Abeta peptide are causative of Alzheimer’s. A huge amount of money has been spent and lost on drugs (antibodies mostly) trying to get rid of the plaques. None have helped clinically. It is possible that the plaque is the last gasp of a neuron dying of something else (e.g. a tombstone rather than a smoking gun). It is also possible that the plaque is actually a way the neuron was defending itself against what was trying to kill it (e.g. the plaque as a pile of spent bullets).