Washington, Nov 23 Johns Hopkins researchers have identified a protein that is responsible for causing chronic rhinosinusitis with polyps.

Chronic sinusitis, a constant irritation and swelling of the nasal passages, is a common condition thought to affect about one out of every six people. This problem has several forms with a range of severities.

One of the most severe forms produces polyps, overgrowths of unhealthy sinus tissue that can block the nose and sinus passages and make breathing through the nose difficult or impossible. This often results in pain, swelling, and an increase in infections.

Researchers have identified a protein called vascular endothelial growth factor, or VEGF, responsible for the cell overgrowth in the development of polyps.

"This type of sinusitis isn't subtle-you can spot the patients with polyps from across the room. They're breathing through their mouths, they talk with nasal voices, they're constantly sniffling, and their faces are swollen," said Dr Jean Kim, assistant professor in the Departments of Otolaryngology and Allergy and Clinical Immunology at the Johns Hopkins University School of Medicine, and a researcher at the Johns Hopkins Allergy and Asthma Centre at the Johns Hopkins Bayview Medical Centre.

"Once the patient has entered the cycle of growing polyps, it's very hard to get out," she added.

The researchers have long studied sinusitis, often growing sinus cells isolated from patients in petri dishes. After noticing that cells from patients with polyps typically multiplied faster than cells from normal patients, the researchers speculated that cells from polyp patients might be producing extra amounts of some type of growth factor, a protein that encourages cell growth.

To identify which growth factor might be to blame, the researchers had sinusitis patients with and without polyps rinse their sinus passages with a wash solution, then tested the runoff for the presence of various growth factors.

They found that solution from patients with polyps contained high amounts of a substance called vascular endothelial growth factor, or VEGF, a protein important for normal blood vessel growth that also seems to play a key role in a variety of diseases, including cancer.

The more VEGF they found in a cell culture, the faster those cells grew.

"It's a strong indicator that VEGF is indeed responsible for the over-exuberant cell growth that contributes to polyp development," Kim said.

The study appears in American Journal of Respiratory and Critical Care Medicine. (ANI)