June 4, 2009 -- A drug derived from an herb used in Chinese medicine for 2,000 years is the first to target specific cells that are overactive in rheumatoid arthritis, psoriasis, and other autoimmune diseases.
The ancient herb is chang shan, from the root of the blue evergreen hydrangea. It's been used in Chinese medicine to reduce fever and fight malaria.
The herb's active compound, febrifugine, is too toxic for use as a modern drug. In the 1960s, U.S. Army scientists created a febrifugine derivative called halofuginone as a possible malaria drug, but further study was soon discontinued.
That may be because the drug's target -- a specific kind of immune cell called a Th17 cell -- was identified only in 2006. But now Harvard Medical School researchers Mark S. Sundrud, PhD, Anjana Rao, PhD, and colleagues show that halofuginone does indeed inhibit Th17 cells.
That's important, because Th17 cells regulate autoimmune inflammatory responses. That's the kind of immune response that goes haywire in a wide range of diseases such as inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, type 1 diabetes, eczema, and psoriasis.
"Halofuginone may herald a revolution in the treatment of certain types of autoimmune and inflammatory diseases," Rao says in a news release.
Why? Current drugs for autoimmune diseases take a sledgehammer approach. They smash down many different immune responses, leaving patients vulnerable to infections and cancers.
A drug that can specifically inhibit one type of immune response would be a major breakthrough. Halofuginone may turn out to be such a drug.
"This is really the first description of a small molecule that interferes with autoimmune pathology but is not a general immune suppressant," Sundrud says in the news release.
An added bonus: Halofuginone could probably be taken orally, rather than by injection.
Yet the findings by Sundrud and Rao are based only on mouse studies. They must be refined and confirmed in humans before any actual drug is developed.
Sundrud and Rao report their findings in the June 5 issue of Science.