All patients were monitored for a minimum of nine months to see if polyps and their resulting symptoms returned. Ten in the surgery group had their polyps return within six months, while 12 remained symptom free.
The Hopkins team took samples during surgery of the mucous membrane lining the nose, and using real-time polymerase chain reaction tests, analyzed the samples for any genetic differences between the groups.
When researchers initially compared all the nasal tissue samples, they found that half had the gene for AMCase turned on, or expressed, to make the chitinase protein. During follow up, they found that the 10 patients who had their polyps return had exceedingly higher levels of AMCase expression than the other sinusitis patients and controls. Gene expression of another inflammatory protein, called interleukin-13, already known to be high in asthmatics, was also found to be elevated in those with polyps, but the levels of interleukin-13 did not have the same predictive value as the elevated expression of AMCase, researchers say.
Lane adds that future research will have to determine if high genetic expression of AMCase is an underlying cause of inflammation or if AMCase is simply one of many chemicals produced by cells in the nose in response to chronic inflammation.
The next phase of their research, he says, is to look for what triggers the anti-parasite response. However, Lane cautions that this reaction against parasites may come at the expense of the nose's ability to ward off other invaders, such as bacteria, viruses or fungi.
"The epithelial cells lining the nasal and sinus cavities play an important role as first responders of the immune system," he says. "But when they are distracted fighting non-existent parasites, they cannot deal well with the very real microbes continuously coming into the nose."