Image: CORDISResearchers in Italy have discovered that the flu virus can contribute to the onset of diabetes. This finding could help scientists uncover a way to prevent some forms of this condition. The study was funded in part by the FLUTRAIN (Training and technology transfer of avian influenza diagnostics and disease management skills) project, which received EUR 1.8 million under the Policies Thematic area of the EU's Sixth Framework Programme (FP6).

Diabetes results when cells fail to take up sugar from the blood. This phenomenon is triggered when cells become insensitive to the hormone insulin, which in turn results in type 2 diabetes. Studies have identified a relationship between diet, lifestyle and type 2 diabetes. Other studies also found that type 1 diabetes is triggered when the immune system plays havoc on the pancreatic cells that produce insulin. Individuals diagnosed with type 1 diabetes have a genetic predisposition to this disorder.

For almost 40 years, scientists have postulated that viruses could be responsible for diabetes. Type 1 diabetes, for instance, usually sets in just after an infection. However, there evidence confirming this has been insufficient, until now.

The New Scientist reported that a team of researchers led by Ilaria Capua from the Italian office of the World Organisation for Animal Health investigated the flu virus in turkeys because these birds with flu often have an inflamed pancreas. Regardless if the turkeys have strains of the virus that do not normally spread outside of the lungs, the researchers discovered that many of the turkeys developed severe pancreatic damage and diabetes. They later infected human pancreatic tissue with two common flu viruses, and both “grew really well” in the tissue, Capua says.

According to the researchers, production of a set of inflammatory chemicals was generated by the presence of flu in the pancreatic cells. The chemicals play an important role in autoimmune reactions that result in type 1 diabetes. The New Scientist reported that some researchers believe immune cells present bits of the infected tissue to destructive T-cells, to help them recognize the virus. However, the T-cells also learn to recognize the cells that make insulin, and to destroy them.

With respect to the flu being present in the pancreas, Capua says the pancreas provides an environment that allows the virus to replicate.

The Italian researchers are now investigating the effects of flu on mouse models of type 1 diabetes and are probing recent flu infection in patients recently diagnosed with the condition. “The great thing is that even if flu only causes a few percent of type 1 diabetes cases,” says Capua, “we can vaccinate and prevent flu in people who are genetically predisposed, and that can have a real impact.”