Gene therapy moves closer

A report from the Royal Society of Chemistry describes a potential new treatment for Crohn's that has shown promise in mice. RNA interference, a recently developed method of gene therapy, was used to suppress a gene that causes inflammation in the intestine, thus reducing the related symptoms.

RNA interference involves introducing into cells a double strand of RNA corresponding to the nucleic acid sequence of the target gene. This causes the destruction of the equivalent messenger RNA so 'silencing' the gene and preventing expression of the relevant protein.

Its discovery in 1998 by Andrew Fire and Craig Mello earned them the 2006 Nobel prize for medicine. But although their discovery has become a vital technique for molecular biology research it has not yet fulfilled its potential as a therapeutic method.
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When RNA was injected into mouse with colitis there was a dramatic reduction in intestinal tissue damage and suppression of leukocytes cells invading the gut wall. The mice were also able to absorb food through their gut wall again and started to regain weight. The team found that their results were due to a drop in the level of two cell signalling molecules (cytokines), TNF-alpha and IL-12, that normally drive inflammation and are produced as a result of cyclin D1 synthesis. They also found that the mice were making more of a protective cytokine called IL-10.

There is a long way to go until this research leads to a safe treatment in humans. For example, at this time not all of the genes involved in Crohn's have been identified. I'm sure that gene therapy would want to be as specific as possible to reduce unintended side-effects.