The mechanisms for RA and AS seem to be quite different and it sounds like consensus is building that they are basically two different diseases so I guess this report isn't surprising.
It's funny that before I had a firm diagnosis, when spondy was still a possibility, my rheumy said "autoimmune arthritis" and the treatments are pretty much the same so we don't really have to worry about which it is. That is becoming clearly an incorrect approach!
I think the closer we move to the genetic root of the disease the more the treatments will differ. TNF is pretty far down the genetic ladder so it makes sense it helps both RA and AS. (although it seems to help AS better than RA) Move up one step to IL 17 and we see less overlap. Move up to IL 23 and I doubt it will help RA at all but may prevent AS symptoms.
RA research really seems to be hitting on IL 6. Acterma I think is now out for RA and in trials for AS. I wonder if it will not work really well for AS? IL 6 has not been implicate din AS. but it may be in teh chain of inflammation somewhere and play a secondary role in AS.
