"This strikingly teaches against what has been thought worldwide about the origin of chronic sinus infection: that inflammatory cells break down, releasing toxic proteins into the diseased airway tissue," says lead researcher and Mayo Clinic ear, nose and throat specialist Jens Ponikau, M.D. "Instead we found that these toxic proteins are released into the mucus, and not in the tissue. Therefore, scientists might need to take not only the tissue but also the mucus into account when trying to understand what causes chronic sinus infections and probably other airway diseases."
The findings could significantly change the way chronic sinus infection is treated, according to Dr. Ponikau.
"This has far-reaching implications," says Dr. Ponikau. "This suggests a beneficial effect in treatments that target primarily the underlying and presumably damage-inflicting nasal and sinus membrane inflammation, instead of the secondary bacterial infection that has been the primary target of treatments for the disease. Also, some surgeons have already started to change the way they do surgery for patients with chronic sinus infections, focusing now on removing the mucus, which is loaded with toxins from the inflammatory cells, rather than the tissue during surgery. Leaving the mucus behind might predispose patients for early recurrence of the chronic sinus infection."
Dr. Ponikau conducted this research along with Hirohito Kita, M.D., and Gail Kephart, Mayo Clinic allergic diseases researchers. David Sherris, M.D., and Eugene Kern, M.D., both former Mayo Clinic ear, nose and throat specialists who now work at the University at Buffalo, also participated in the project.
The team found that in chronic sinus infection patients, activated white blood cells (eosinophils) cluster in the nasal and sinus mucus and scatter a toxic protein (major basic protein) onto the nasal and sinus membrane. While major basic protein was not distributed in the nasal and sinus tissue, the level of this protein in the mucus of chronic sinus infection patients far exceeded that needed to damage the nasal and sinus membranes and make them more susceptible to infections such as chronic sinus infection.
To conduct this investigation, Dr. Ponikau and fellow researchers collected specimens from 22 consecutive Mayo Clinic chronic sinus infection patients undergoing endoscopic sinus surgery. The surgeons extracted the maximum possible tissue and mucus during the sinus surgery. The surgeons also extracted tissue and mucus from healthy patients undergoing septoplasty, surgery to fix a deviated septum, for comparison with the specimens from the chronic sinus infection patients. Through various forms of laboratory examination of the tissue and attached mucus, the investigators observed an abundance of major basic protein throughout the nasal and sinus mucus in all 22 specimens, but not in the tissue.
Chronic sinus infection is one of the most common chronic diseases in the United States, affecting 32 million adults, according to the National Center of Health Statistics. Chronic sinus infection produces nose and sinus problems characterized by stuffy nose, loss of sense of smell, postnasal drip, nasal discharge, and head and face pain lasting three months or longer. It notably decreases the quality of patients' lives, impairing physical and social functioning, vitality and general health, according to the Mayo Clinic researchers.