TPO ANTIBODIES ONLY

So I need some insights and truths about TPO antibodies. I’ve heard a lot in the traditional and hollistic medicines areas. One, why is it that there are 100+ autoimmune diseases, yet they receive the lowest amount of research, and we are literally in an autoimmune pandemic at this point. Not myths, just do a little research as this is not the point of my post. But let’s say a patient has “normal range” for everything, TSH, T3, T4, vitamin levels are great, but they have very high TPO antibodies attacking the thyroid? So what is it that initially caused these antibodies to be present and two what caused them to start attacking the thyroid? And how is it not possible to eliminate an anti-body that wasn’t there before?