In the September 2006 issue of Nature Cell Biology, Deborah Nelson and colleagues show that CFTR - cystic fibrosis transmembrane regulator, the protein that malfunctions in cystic fibrosis - can control the acidity of digestive compartments in the cell, causing a defect in their ability to kill bacteria.
Bacterial infections in the lungs of cystic fibrosis patients can cause chronic inflammation, which in turn induces tissue damage and worsens the symptoms of the disease. One way that cells clear bacterial infection is through phagocytosis - where specialized cells, called macrophages, ingest the bacteria and destroy them by digestion in acidic compartments. The authors found that CFTR, a chloride ion channel, is present in particular macrophage cells that function specifically in the lung. Using macrophages obtained from mice that are genetically engineered to no longer express the CFTR protein, or by specifically inhibiting CFTR, the authors show that there is a defect in acidification of the digestive compartment in the cell. As a result, an alkaline environment persists, permitting bacterial growth and division.
Macrophages are a key player in the body's defence mechanism. Compromising their function, as shown by Nelson and colleagues, may begin to explain the persistent infections observed in cystic fibrosis patients
Deborah J Nelson (University of Chicago, IL, USA)
Abstract available online.
(C) Nature Cell Biology press release.
Message posted by: Trevor M. D'Souza