NEW YORK (Reuters Health) - Some of the most successful treatments for rheumatoid arthritis work by blocking an inflammatory factor called tumor necrosis factor or TNF, and now Dutch researchers have shown in animal experiments that the treatment can be delivered by gene transfer.

As senior investigator Dr. Paul P. Tak told Reuters Health, the findings "show that gene therapy using a novel virus encoding a TNF inhibitor injected into the inflamed joints may be a safe and feasible approach for the treatment of rheumatoid arthritis."

In their experiments, reported in the Annals of the Rheumatic Diseases, Dr. Tak of the University of Amsterdam and colleagues used a modified virus encoding the gene for the receptor of human TNF. They theorized that once the gene was expressed, the product would in essence block the TNF activity that leads to inflammation.

When the gene-carrying virus was injected it into the joints of rats with induced arthritis, there was a significant reduction in paw swelling in treated animals, the investigators report.

Given these encouraging findings, Dr. Tak and his co-investigators "are developing this approach for use in patients."