Anecdotally, nightshade[1] sensitivity seems to be common among people with autoimmune disease and nightshades are one of the anti-recommended foods on the Paleo Autoimmune Protocol, so I think this hypothesis carries some weight.
My personal experience is with Celiac disease and Hashimoto's thyroiditis, and nightshades absolutely destroy me.
[1]Which includes chili peppers, bell peppers, tomatoes, eggplants, and potatoes.