LONDON (Reuters) - Using drugs or diet to boost a protein to restore the body's natural defences to gut infections may offer a new way to treat currently incurable bowel diseases such as Crohn's disease, European scientists said on Monday.

Researchers led by scientists from the Pasteur Institute in Lille, France, found that having low levels of a protein called PPAR-gamma, which regulates defences that kill bacteria in the gut, may make patients less able to fight off gut infections — so boosting PPAR-gamma could help protect against such diseases.

Mathias Chamaillard, who led the study, said in a telephone interview the results showed that drugs already used for other diseases could prove effective in Crohn's disease.

For example, GlaxoSmithKline's diabetes drug Avandia, known generically as rosiglitazone, has been shown to restore gut defences through PPAR-gamma activation, he said, and Takeda Pharmaceutical's Actos, or pioglitazone, another PPAR drug used in diabetes, acts in the same way.

Inflammatory bowel conditions such as Crohn's disease and ulcerative colitis affect around 0.5 percent of the population in developed nations and are notoriously difficult to treat.

Treatments include a group of injectable drugs that block an inflammatory protein called tumour necrosis factor (TNF) such as: Johnson & Johnson's Remicade, Abbott's Humira and UCB's Cimzia, but Chamaillard said not all patients respond to these, and others find they stop being effective after time.

The European team, whose work was published in the Proceedings of the National Academy of Sciences (PNAS) journal, used mice engineered to be low in PPAR-gamma and found they were less able to fight off bacterial infection in the colon compared to normal mice.