Chloroquine, Insulin and Inflammation
Your humble reporter was fascinated to read about some new research using the anti-malarial agent chloroquine as a potential treatment for the insulin resistance syndrome.
I have a personal reason for being interested. Hypoglycemia (low blood glucose) is an occasional feature of treatment with chloroquine and in 1980 a study first indicated that chloroquine might slow the break down of insulin by the liver. In the early 1980s there were a flurry of papers indicating that chloroquine did some subtle things to insulin and insulin receptors in many tissues. So we came up with the idea of measuring its effects in humans. There was a memorable occasion on which I was doing an outpatient clinic with an intravenous line in my arm. (English doctors are well known for doing experiments on themselves: I had a professor in medical school who said that you should never do to a patient what you haven’t had done to yourself. I shall leave it to you, gentle reader, to wonder if I’ve tried everything….).
So there I am doing my clinic when, around 11AM I begin to feel really strange: my glucose level was almost unrecordable and my insulin level was off the chart. Nothing that couldn’t be solved with a large dollop of sugar, but it made me very sympathetic to people who get hypoglycemic from their regular treatments.
Sometimes Nature does our experiments for us: we did a lot of work on diabetes because it is associated with high rates of vascular disease. So understanding the mechanisms by which diabetes does that may help illuminate some of the cellular disturbances underlying arteriosclerosis in general. We are also interested in the few illnesses in which a single disturbed gene may lead to a definable set of signs and symptoms. There is a rare illness known as ataxia telangiectasia in which sufferers have a high risk of developing some cancers particularly lymphomas and leukemia. People with the illness are very sensitive to ionizing radiation, have a specific type of immune deficiency, degeneration of parts of the brain related to muscle function and coordination and they age prematurely. More than ten years ago it was discovered that a single gene – ataxia-telangiectasia mutated (ATM) gene – was responsible for the illness. The gene is responsible for producing a protein that recognizes damage to DNA. It now seems that ATM may also be linked to metabolic and cardiovascular diseases. It does this by inhibiting a protein called JNK, a stress kinase involved in inflammation with related effects in insulin resistance and atherosclerosis. So to everyone’s surprise a gene that can cause a rare disease can also cause insulin resistance.
In the November issue of Cell Metabolism, researchers at Washington University School of Medicine in St. Louis and St. Jude Children’s Research Hospital in Memphis, Tennessee report that a small dose of chloroquine eased many symptoms of metabolic syndrome in mice, reducing blood pressure, decreasing hardening and narrowing of the arteries and improving blood sugar tolerance. The results suggest we may only need very low and perhaps infrequent doses of chloroquine to achieve similar effects in humans. Both insulin and chloroquine activate the ATM gene.
This adds to the data that some of the metabolic dysfunctions triggered by obesity may be linked to the inflammatory responses that go wrong in autoimmune disorders like arthritis and systemic lupus erythematosus.
And an older treatment for rheumatoid and lupus just happens to be chloroquine.
Chloroquine itself has some side effects, but this is important information that will help us design more effective and carefully targeted holistic treatments for both metabolic disturbances and inflammatory conditions. All in all, very good news indeed.