These things didn't exist ~120 years ago. So even if it as autoimmune disease it's caused by something new: and this all started (and can be healed to a certain or complete degree) via sugar elimination.
So "autoimmune disease" is downstream from sugar consumption.
Also, most of what we call "autoimmune disease" is BS: eg when they say that T1 diabetes is autoimmune they actually found damaged protein in the pancreas cells and the immune system was actually saving the pancrease from those damaged proteins.
But if the diet is bad those damaged proteins will keep being shuffled there: so it's not the immune system that hurts you: it's the chronic poisoning of tissue with stuff that should not be there -> then over time the immune system does some colleteral damage which compounds due to the chronic toxicity -> so the problem is chronic toxicity, not "autoimmune".
The same is true for arthritis: you can find stuff that should not be in the joint capsule there for people with arthtiris: the immune system then over time does some damage as it tries to save the joint from the foreign bodies which are chronicaly accumulated.
TLDR: autoimmune disease is mostly pure BS, it's chronic toxicity. It's just that we know how to detect white blood cells (WBC) betters in the blood than other (yet unknown) substances.
BUt just because you see a higher WBC count doesn't mean it's autoimmune: it's just that you can't find the real reason why WBC are activated.
About the gut: modern processed food is so unnatural that it destroys the gut barrier -> so again, not an autoimmune disease, but a pure food induced disease.
The stuff starts leaking from the gut into the blood which poisons the body (and the liver primarly, but from the liver it spreads into the blood).