A group of scientists from the Institute of Molecular Biology of Barcelona (IBMB-CSIC), –located at the Barcelona Science Park-, the University of Pittsburg and the Brigham and Women's Hospital of Boston (USA) have identified a new defence mechanism of lung cells to fight off bacterial infections, such as pulmonary emphysema or pneumonia.

The research, which has been published in the last issue of Nature journal (doi:10.1038/nature08181) helps to understand the defence mechanisms of the human body to fight off bacterial attacks and could result in new antimicrobial therapies.

The study, in which researcher F. Xavier Gomis- Rüth, of the IBMB-CSIC has participated, is focused on the matrix metalloproteinase 12 enzyme (MMP-12). This enzyme, expressed by macrophages (a type of white blood cell) of the lung, presents antimicrobial activity. In fact, its implication in diseases such as pulmonary emphysema is well-known, but until now there had been no data on its exact role. This work, to which CSIC research has contributed, describes its mechanism of action and determines the domain of the responsible protein.

The researchers based their work on the hypothesis that MMP-12 was involved in the defence mechanism against bacteria. To confirm this, the team performed a trial with two groups of rodents, one normal and the other genetically modified so it would not produce the MMP-12 enzyme. After exposing both groups to a bacterial infection by S. aureus and E.coli, two model bacteria widely used in scientific projects, the authors concluded that the group of rodents without MMP-12 had a 50% higher mortality due to infection in the lungs and peritoneum. In subsequent trials, rodents without MMP-12 also showed higher mortality in the case of pneumonia.

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