Another pro-inflammatory cytokine: IL-17

About a month ago I read a Science Daily article with an intriguing title: “Protein’s New Role Discovered In Autoimmune Disease.” (see: In a nutshell, University of Alabama researchers identified a previously unknown effect of a T cell-derived cytokine named interleukin-17, or IL-17 for short. This is an “immunity protein,” that helps induce and mediate pro-inflammatory responses, such as allergies, autoimmune diseases and whatnot. IL-17 also induces the production of many other cytokines, such as the infamous IL-6! Uh-oh!

Now, the news reported in Science Daily is that when the “messenger” signals from IL-17 were blocked, the disease-causing B cells dropped from 17 to 2 percent. Coincidence? Ah, no. As the articles states, “The drop was a clear sign that IL-17 plays a major role on shaping B cells’ ability to create more and more disease-causing antibodies.” So if IL-17 can be inhibited, B cells are slowed down in their efforts to create wacky antibodies. And here I thought B cells were the good guys, the cells that defend us against infections etc. Well, in autoimmune diseases they can go bonkers, as we can read in the Science Daily article.

After reading this article, I immediately checked out if IL-17 is involved in myeloma. Of course it is. Hah, figures! For instance, see the abstract of this 2006 study (, which shows that IL-17 “is a CD4 T-cell-derived mediator of angiogenesis that stimulates vascular endothelial cell migration and regulates the production of a variety of proangiogenic factors, such as tumor necrosis factor-alpha (TNF-alpha) and vascular endothelial cell growth factor (VEGF).” Need I add more? Oh, ok, just this bit: the researchers conclude that “IL-17 plays a role in the promotion of angiogenesis and associated disease progression in MM.” Bad, bad IL-17!

I found an interesting bit of information on IL-17 in the MD Anderson October 31st 2005 “Weekly News and Notes for Patients, Families and Visitors.” The article is titled “New immune cell found to be a key to inflammatory diseases” (see: MD Anderson and other researchers discovered a new type of T-cell, called THi, produced IL-17, which they “linked to an immune system gone awry." An awry immune system? Well, if that doesn’t sound familiar…! Before this discovery, IL-17 was known to play a role in autoimmune and inflammatory diseases, but its origin was a mystery. The study’s lead investigator stated that “These findings suggest that shutting down the activity of these THi cells might stop chronic inflammatory diseases from developing in the first place.” How about that?

Okay, IL-17 is now officially on my list of evil pro-inflammatory cytokines. It is also connected, by the way, to NF-kB (I need to do more research on this topic; I may get to it, someday…). IL-17 also stimulates IL-8, which is an angiogenesis cytokine in myeloma. This reminds me that one of my future projects is to create a permanent page listing all of these pro-inflammatory cytokines and their role in myeloma progression. Eh.

I would like to end today with a question: is there anything that we can do to inhibit IL-17? Or could we already be doing something? The answer to this question will be in tomorrow’s post. Oh, and tomorrow is "medical day." I am seeing my haematologist at noon (with a list of questions as long as the highway between Florence and Bologna), then my family doctor in the afternoon (shorter list of questions). I imagine I will have quite a long post tomorrow! 

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