22nd March 2018
A year ago, I wrote a blog suggesting that lead – as in the element – could have caused/causes a great deal of cardiovascular disease. I went further, to propose that the removal of lead as an additive in petrol (gasoline) may have been responsible for a significant percentage of the decline in cardiovascular disease in the Western World, over the last forty or fifty years.
Last week a paper was published suggesting that excess lead was responsible for as many deaths as smoking 1. So, there you go, it turns out I was right. Once again. Yes, yes, I know, Nobel prize on the way. Or perhaps not.
In fact, what cheered me most about this study is that my hypothesis that endothelial damage is the trigger for CVD, was strongly supported. Some time ago I set about looking for factors/things that were capable of damaging the endothelial cells that line arteries. I tend to do this by going to Google and typing in the words endothelial damage ‘and’ copper, or lead, or mercury, or glucose, or smoking, or sickle cell anaemia etc. etc.
Then I see what pops up. At which point I switch to PubMed to look for the associated papers in the area. As it turned out when you hit lead and endothelial damage there was not a great deal, but it is fascinating, and it is clear that lead does damage endothelial cells, in various ways. It also damages many other things in the body – but that is another story.
This relatively unstructured searching system is how I ended up looking at chelation therapy. This form of treatment is/was supposed to remove heavy metals, such as lead, from the body. I had written it off as ‘woo-woo medicine’ (a phrase I actually hate, but I thought it was appropriate here). So, you use drain cleaner in arteries and this makes you better. Yes, right, pull the other one. Bong, next.
Oh well, you live and learn. Turns out that chelation actually works2.
The second thing about the latest paper demonstrating the impact of lead on CVD is that the endothelial damage conjecture had proven ‘predictive’. The best scientific hypotheses are those you can use to predict what is going to happen in the future or better explain the facts of what happened in the past.
As an example of a good predictive hypothesis, we know that if we stand in a specific place, at a specific time, we will see an eclipse of the sun. We know this because we have been told that it will happen by people, who get this right 100% of the time.
If, on the other hand, someone says global temperature will rise by two degrees in the next twenty years, and it does not, we should be rightly sceptical that the scientists predicting this have got their ideas properly nailed down. We should also be sceptical when people alter their hypothesis to fit the facts. Global Warming has become Climate Change. Which some, like me, would say has changed their hypothesis from one that can be disproven, to one that cannot. ‘We predicted the Climate would change, and look it has. Told you so.’
‘Well gee whizz that was just so extremely helpful. Thanks.’
Anyway, to get back to endothelial damage. My conjecture is that, if you can find a factor that damages the endothelium, you will find that it increases the risk of CVD. It is not enough to say that most things that damage the endothelium increase the risk of CVD, or that almost everything that damages the endothelium increases the risk of CVD. It has to be everything.
There are, of course, provisos. We know that smoking increases the risk of lung cancer. We also know that some people who smoke never get lung cancer. So, on an individual basis, there can be protective things going on. Ergo, I would not expect everything that causes endothelial damage to cause CVD, in everyone.
Equally, we know that the tuberculous bacillus causes TB. However, not everyone that is exposed to the bacillus gets TB. We also know that people who carry the gene for CCR5 delta 32 mutation cannot be infected with HIV or Ebola. Why not? Because their cells do not code for the protein that allows these viruses to gain entry to cells. Just thought I would throw that one in. I am not just interested in CVD, you know.
In reality, there is almost nothing that is both necessary and sufficient to cause disease, or death – in everybody. Some people have survived falling out of aeroplanes without a parachute. Not many, but it has happened. Ebola kills up to 80% of those it infects, but some survive.
So, what I spend a lot of time doing is attempting to establish is whether or not endothelial damage is ‘necessary’ for CVD to develop [not that it is sufficient in everyone]. Or as someone told me on the blog ‘If and only if.’ As in, CVD will develop if, and only if, endothelial damage has occurred.
So, are there contradictions to the endothelial damage hypothesis? Well, if there are, I have yet to find them. Which does not mean that they do not exist. The closest I have come to a contradiction is with thalidomide. Everyone has heard of this drug, and the terrible malformations it caused. I suspect not many people know why it caused limb malformations.
It is because it interferes with the production and growth of endothelial cells. Because these cells did not grow and develop, blood vessels did not develop and grow in the unborn child, so there was no blood supply to support limb growth. So, the limbs were terribly shortened. I suspect that if thalidomide had been given at an earlier stage of the pregnancy the heart, brain, lungs etc. would have failed to develop and the foetus would have been non-viable – with spontaneous abortion.
Because thalidomide interferes with the formation of new blood vessels (angiogenesis) it is now used to treat cancer, and leprosy, and a few other things as well. Cancers need their own blood supply to grow, and if you stop them triggering new blood vessel growth and development the shrivel up and die. At least, that is the plan.
Other drugs have been developed to stop angiogenesis. One of the first was Avastin. Technically, it is a Vascular Endothelial Growth Factor (VEGF) inhibitor. It inhibits the growth of new endothelial cells. It is also widely used in macular degeneration, where the growth of new blood vessels in and around the macula (the main bit of the retina you use to see with), destroys the vision.
Unfortunately, Avastin has a significant adverse effect. You can probably guess what it is. Yes, it increases atherosclerotic plaque growth, and significantly increases the risk of death from CVD. In high doses, over two years, up to a 1,200% increase in heart attacks3.
Now thalidomide is not exactly the same as Avastin, but it definitely has a negative impact on endothelial cells in some way. But I can find no evidence for thalidomide increasing CVD risk. I can find evidence that, if you give thalidomide to pregnant animals, they too demonstrated limb deformity in offspring. However, if you give Viagra this eliminates the deformity. So, we know that inhibition of nitric oxide (NO) must be a key mechanism of endothelial dysfunction with thalidomide.
Therefore, it should increase CVD risk. Does it, or does it not? Well, you can read this paper ‘Apoptotic signaling induced by immunomodulatory thalidomide analogs in human multiple myeloma cells: therapeutic implications.’4 And try to decide if it does, or it does not. Personally, I cannot figure it out at all. I am kind of hoping that it does, or else my theory is in danger of hitting the waste bin.
Until next time.