Newly Discovered Cellular Defect Is Responsible for Cystic Fibrosis Mucus Build Up

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by Kara Elam |

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P. aeruginosa lung infection in cystic fibrosis

shutterstock_209181739An article published in the Journal of Clinical Investigation provides evidence that challenges the previously held assumptions as to where the abnormal accumulation of sticky mucus, a key feature in cystic fibrosis (CF), originates. The study entitled Defective goblet cell exocytosis contributes to murine cystic fibrosis–associated intestinal disease used an experimental animal model to elucidate the origin, and the findings have the potential to impact the direction of novel treatment modalities to target the excess mucus build up and remove it.

CF is a chronically progressive life-threatening disease caused by a genetic mutation that disrupts the body’s ability to hydrate and effectively clear mucus in the lungs and/or digestive tract. According to the CDC, in the US, approximately 1,000 new cases are diagnosed with more than 75% of those patients under the age of two. An estimated 30,000 children and adults in the US and 70,000 worldwide have the disease. Patients diagnosed with CF have a lifespan of approximately 30 years, with many patients living into their forties.

The genetic mutation that causes CF affects the normal functioning of the lungs and digestive system by creating abnormal amounts of very sticky mucus that covers the lungs, pancreas, and other important organs of the respiratory and digestive systems. This sticky mucus attracts foreign pathogens, such as viruses and bacteria, making patients more susceptible to infectious diseases (ie. pneumonia). The findings of the current study conducted by researchers at the University of Missouri (UM), showed that instead of the mucus build up originating from the linings of the organs, it actually gets stuck inside goblet cells that have now been identified to be responsible for creating the mucus.

Dr. Lane L. Clarke, DVM, PhD, professor of medicine, research investigator at UM’s Dalton Cardiovascular Research Center, and senior author on the study, explained the research in a recent press release stating, “Normally, special cells create mucus and easily push it out to the linings of the organs where it belongs. However, in cystic fibrosis patients, some cells that create the mucus fail to completely release the mucus, so the mucus becomes stuck halfway in and halfway out. This makes mucus clearance more difficult and potentially would allow bacteria to have an easy pathway to infecting cells to cause diseases like pneumonia.”

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The study not only examined the amount and origins of the mucus, but its acidic make-up as well.

In a statement explaining why all of these components of the mucus are important variables to study, Dr. Clark said, “Previously, cystic fibrosis researchers disagreed as to whether cystic fibrosis cells also have a defect in properly acidifying areas inside cells. Finding that cystic fibrosis mucus granules are not acidic is important because the lack of acidity slows the release of products from other secreting cells. Knowing this will allow us to begin further investigation into what causes this lack of acidity, which could eventually be another pathway to developing treatments for this disease.”

For CF patients and their healthcare providers, the more thorough understanding of the underlying cellular pathology gleaned from the study’s findings gives hope that advanced treatments targeting this mechanism will be available in the near future.