I have ankylosing spondylitis as well as neuropathy everywhere. A.S is in the same ' family' as PsA. I had A S first forbyears and then developed the neuropathy. It wasn't drug induced, it came on its own. I dont think there is always a clear connection between autoimmune problems and if you have one you may well get another- not necessarily linked to the first. What makes it all so tough is finding treatment that can address the different autoimmune mechanisms in one hit. Different disease modifying drugs target different mechanisms within the immune system.
I did find that when I took Enbrel for my A.S, the neuropathy was better - everything was better. But not entirely and I felt not enough to continue. I stopped it and now am trying to find the right thing to manage it all.
I developed the neuropathy before Enbrel so there is no connection there.