PAI-1 Is part of the blood to clutching mechanism that coordinates the process of keeping the blood flowing properly in the blood vessels so it balances the process between creating enough sickness in the blood so that it can clot or create blood clots as they are needed.
The way it works fine the blood normally produces an anticoagulant or an enzyme that keeps the blood from clotting called Plasmin, while another enzyme that tries make the blood clot produces Thrombin. The anticoagulant Plasmin is enough to balance the amount of thrombin. Plasmin vs Thrombin amounts are coordinated by PAI-1 or plasminogen activator inhibitor-1. That fine balance is used by the body to increase the blood thickness or coagulation ability by increasing PAI-1.
Thus when we over eat, gain weight, stress overload, or any process that creates more of a burden of any kind on the body, except for exercise, unless the exercise is excessive, then PAI-1 increases to prevent muscle damage.
So anything that is bad, harmful or a load on our physiology or anything that causes a disease or pathology, such as infection, inflammation of any kind will increase PAI-1, cells dividing abnormally such as cancer or even pre-cancerous division, is sensed by the mitochondria and begins producing more PAI-1.
Most individuals have one of three different genetics that control how much PAI-1 is produced for each situation. That genetic tendency has a hereditary and ethnic background, that is passed on to siblings. Thus each region of the world tends to have a specific genetic tendency.