New delivery system for gene therapy may treat autoimmune diseases

Published on 15 May 2012
New delivery system for gene therapy may treat autoimmune diseases

A new technique for administering gene therapy could help to treat autoimmune diseases such as rheumatoid arthritis and lupus, US scientists claim.

Researchers at Georgia Health Sciences University have conducted research on an animal model of rheumatoid arthritis to test their method, which uses a DNA-covered sub-microscopic bead to deliver genes or drugs directly into cells.

The researchers inserted the gene for indoleomine 2,3 dioxygenase (IDO) - an immunomodulatory enzyme that speeds up the degradation of an amino acid called L-tryptophan - into DNA nanoparticles to investigate the enzyme's potential as an autoimmune treatment.

However, they noticed that the DNA nanoparticles themselves were capable of producing the desired result.

Within hours of injecting the DNA nanoparticles, IDO expression increased and the immune response was dulled, significantly reducing joint swelling and inflammation in animals with rheumatoid arthritis.

It is thought that the arrival of the DNA nanoparticles was enough to cause immune cells called phagocytes to increase their production of IDO.

Dr Andrew Mellor, director of the university's Immunotherapy Centre and one of the authors of the study in the Journal of Immunology, revealed: "We want to induce IDO because it protects healthy tissue from destruction by the immune system.

"It's like pouring water on a fire," he continued. "The fire is burning down the house, which in this case is the tissue normally required for your joints to work smoothly. When IDO levels are high, there is more water to control the fire."

At present, the polymer being used to form the nano-beads is non-biodegradable and is therefore not suitable for use in humans.

But the researchers are already working with biopolymer experts at a number of US institutes to identify a suitable polymer that will safely degrade in the body, potentially paving the way for new treatments for rheumatoid arthritis and other autoimmune diseases.

A spokesman for Arthritis Research UK said: "We're aware of the importance of targeted therapies to provide specific treatment and reduce side effects. We are funding similar work looking at ways in which to deliver drugs or possible therapies to specific cells in the joint."