They can get worse because of it.
Increased expression of CTGF in strictured Crohn's fibroblasts underlies its role in fibrosis. TNF-alpha suppresses fibrosis by downregulating fibroblast CTGF expression, an effect that may be lost following anti-TNF-alpha treatment, thereby promoting stricture formation..
http://www.ncbi.nlm.nih.gov/pubmed/16838391
There is a lot of debate back and forth about this, in the beginning many doctors refused to prescribe infliximab to people because they saw every time that there were strictures, then they blamed the coritcosteroids, then they blamed the infliximab (humira), etc.
My opinion is yes, infliximab and humira promote stricturing.
I think why some don't get strictures is because they have no prior stricturing, stricturing can keep going and collagen can increase with or without inflammation once you have a stricture, you could "cure" someone of the inflammatory process but the stricture process can still continue due to collagen deposition. But when someone already has a stricture, using infliximab or humira likely makes it worse.
People with a lot of stricturing tend to be also refractory, they do not tend to respond very well to medication, likely because crohn is not always driving the inflammation, but the stricturing is.
It's not easy to determine where the pain or inflammation is coming from with someone with strictures, it could be coming from the inflammation from crohn, or it could be from the stricturing which is promoting inflammation. If it's the later, then medication usually does very little, many people with heavy stricturing are refractory.
Little children getting crohn is often accompanied with stricturing very early on, I wonder sometimes what the cause is, because in adults stricturing is often a very slow progress, and sometimes even partially reverses itself (because of cell renewal), I wonder if it has to do with the pretty agressive therapy they use for children now, many kids are immediately put on humira or infliximab. In the past this wasn't the case, but I also heard far less about stricturing.
