Bacteria living in our intestines may be a key to fighting obesity. Now, researchers have found one protein on the surface of white blood cells that plays an important role in controlling these bacteria.

It may sound disgusting and unsanitary, but the guts of mammals are teeming with bacteria. These gut-bugs help us digest food, provide us with nutrients and keep harmful bacteria away — actually playing an integral part in our health. Every person has different types and proportions of bacteria, almost like a fingerprint. Recent research has been pinpointing the role of this "microflora" as the key to understanding obesity and inflammatory bowel diseases.

Toll-like receptor 2 (TLR2) is a protein on the white blood cells (the body's defenders against viruses and other pathogens) living in the lining the large intestine. It reaches out and recognizes the microbes that live around it, sending this information into the cell and directing it to either attack or ignore the bacteria. The new study found that when TLR2 isn't working correctly, people seem to be resistant to obesity, but they are also more susceptible to inflammatory bowel diseases, including ulcerative colitis.

Richard Kellermayer at Baylor College of Medicine thinks that TLR2 mediates these conditions by turning on and off a certain genes in response to what bacteria are residing in their guts. But TLR2 also can significantly alter the bacteria present in the gut, he said. "This remarkable capacity may provide means for the prevention and optimized treatment of common metabolic (such as obesity and diabetes) and gastrointestinal disorders," Kellermayer said in a statement.

Kellermayer and his team compared normal mice to genetically altered mice without TLR2. They saw changes in the type and relative proportions of bacteria in the gut as well as changes in the expression of genes related to inflammation. Without TLR2, the mice's gut microbes resembled those of lean animals, though they were more prone to colitis-like diseases, meaning this gene plays an important role in both obesity and inflammatory diseases of the intestines.

Learning more about how our genes and proteins interact with our gut bacteria may give researchers a better idea of how to keep our intestines healthy, the researchers said. Finding a way to optimize gut microflora and immune system activity (white blood cells) to reduce obesity without causing gastrointestinal problems could open new avenues of research into these metabolic and inflammatory diseases, they added.

This study was published online ahead of print on Jan. 12 in the journal FASEB.