The extremophiles are at home in near boiling water and the deep crust of the earth. Every ecological niche is colonized by life; and life forms everywhere work to change their ecology to suit themselves.
It is the inevitable logic of natural selection in action.
So then, why should the hot tissues of auto-immune disease be any different? How could there not be life forms evolved to that extreme environment? Life forms that might facilitate it, to defeat their enemies and extend their preferred environment. An ecology that, once created, will host competitors, some liking it hotter, some coder. An ecology with successor species, like any forest.
It seems inevitable.