Recruitment of leukocytes to atherosclerotic lesions in vivo
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: More cigarette smokers die of a heart attack than die of cancer or any other single cause. The exact sequence of events that link cigarette smoking to an increased susceptibility to athero-sclerosis, the blood vessel disease that triggers the heart attack, remains uncertain but there is some evidence that smoking cigarettes may increase oxidative damage to the cholesterol-carrying molecules, the lipoproteins (more specifically, the low density lipoproteins--LDL). Uptake of oxidized LDL by cells in the artery wall may be the main way in which cholesterol builds up. Another effect of oxidized LDL is to play a part in the recruitment of circulating white blood cells into the damaged artery. While a good deal has been learned about the several molecules to which white blood cells stick and the molecules that can attract them into the artery wall, the relative importance of these has yet to be properly tested in the whole animal. This is because methods have not been available that are sensitive enough and specific enough.
 
 
 
 
 
 Molecular biologists have developed a remarkable method that makes it possible to make literally millions of exact copies of a gene (DNA) in just a few hours. Although currently available methods for measuring DNA are not nearly sensitive enough to measure the small quantities of DNA present in individual cells, we can easily measure the quantity present in three or four million copies of DNA molecules. This method, known as the polymerase chain reaction (PCR), can be carried out in such a way that only one specific gene in a large mixture of genes will be copied. For example, if two cells have differently constructed forms of a particular gene, we can set things up so that only one form of the gene is copied. The basic trick then is to introduce a known number of white blood cells from a donor animal into the blood of another animal that totally lacks one of the genes present in the donor’s white blood cells. The genes are otherwise as nearly as possible identical. The PCR test is set up so that it will detect only the donor white blood cells. Using this method we have shown that we can detect even one donor white blood cell in the presence of a million other cells and can in fact measure the very small number of white blood cells that enter a particular damaged area of a blood vessel in the course of a day.
 
 
 
 
 
 
 
 Using this novel approach, we believe we will be able to demonstrate for the first time the natural history of the entry of white blood cells into atherosclerotic lesions, determine how long they persist in a lesion, and identify the key molecules that control this entry of cells and their survival. If we could identify the most important molecules involved, there would be the hope of developing drugs that target those molecules and thus slow the process of atherosclerosis. Such drugs could be used in conjunction with cholesterol-lowering regimens and should give additive protection. Finally, we will test the hypothesis that smoking increases the heart attack rate by increasing the oxidation of lipoproteins, as discussed above. We will test this possibility by exposing mice to cigarette smoke just before injecting white cells from a donor and see if the rate of entry of white cells into the lesions is increased. If so, we will then determine whether or not pre-treatment with antioxidants prevents this increase in white blood cell entry into the damaged artery.