What are possible autoimmune disorders/diseases that can cause or make major depression worse if psychological and medical reasons are ruled out?

Autoimmune=medical: When you say psychological and medical reasons are "ruled out, " you are eliminating all disorders and diseases (including autoimmune ones) from consideration. If i may put some back in, systemic lupus and rheumatoid arthritis come to mind as worsening depression. In fact a flare of sle may be heralded by an exacerbation of depression. Steroid treatments of these can be depressogenic as well.

Autoimmune/Depressio: Most are chronic, debilitating & life-threatening, hence more likely to cause or worsen depression. There are more than 80 illnesses identified as autoimmune, and among those on top of list are diabetes, crohn's disease, cushing's syndrome, lupus, graves' disease, myasthenia gravis, ms, psoriasis, sarcoidosis, rheumatoid arthritis, ulcerative colitis.