This is a good article about the use of VDR agonists to treat autoimmune disease: http://onlinelibrary.wiley.com/doi/1...bmr.07s217/pdf
The treatment I'm on uses olmesartan as the VDR agonist, and you limit your blood levels of vitamin D to reduce the level of the hormone 1,25D (short for 1,25(OH)2D3). It is replaced by olmesartan which binds into the VDR.
When I had my vitamin D measured, my serum vitamin D was low, but my 1,25D (the active metabolite) was high. It is not common to test for 1,25D, which is why very often people have low vitamin D and are considered vitamin D deficient. If they tested for the active metabolite it could show otherwise. The theory is that most people with AI disease seem to be D-deficient, but it is a result of and not the cause of the disease, and is dysregulated in AI disease.