Asthma, cystic fibrosis (CF) and chronic obstructive pulmonary disease  (COPD) are serious and even life-threatening conditions. However, these  health problems share something with a usually minor infection -- the  common cold. The connection? Rhinovirus (RV), a single-stranded RNA  virus from the picornaviridae family, causes the majority of  colds and RV is also known to trigger exacerbations of CF, asthma and  COPD.
But now University of Michigan at Ann Arbor scientists  have found that a natural substance, the flavonoid quercetin, puts the  brakes on the ability of RV to replicate. It also fights inflammation.  According to their research just presented at the American Thoracic  Society (ATS) 2010 International Conference held in New Orleans, quercetin  could be a treatment for rhinovirus-caused infections and could be  particularly beneficial for people with serious underlying chronic lung  diseases.
That's great news not just for people looking  for a possible cure for the common cold but especially for those  suffering from conditions like COPD and CF that rob them of the ability  to breathe. For example, COPD (which includes emphysema and chronic  obstructive bronchitis) causes coughing, wheezing, shortness of breath,  chest tightness, and other symptoms. According the National Heart, Lung  and Blood Institute, COPD is a major cause of disability and the fourth  leading cause of death in the United States. CF is an inherited chronic  disease that affects the lungs and digestive system of about 30,000  children and adults in the US. It causes the body to produce a thick,  sticky mucus that clogs the lungs and can lead to life-threatening lung  infections.
For their study, the University of Michigan research  team decided to test quercetin on cells infected with RV. A  phytochemical found in the skins of apples, red onions and other foods,  quercetin is known to be a powerful antioxidant with antihistamine and  anti-inflammatory properties. So the scientists hypothesized that  quercetin might reduce the ability of RV to spark an inflammatory  response. That's important because inflammation causes oxidative stress  which can disrupt the function of epithelial cells (cells that line  cavities and structures) inside airways, negatively impacting the  ability to breathe.
Their lab experiments with RV infected cells  showed that the researchers were right. The results suggested that  quercetin actually inhibited the ability of the virus to replicate. The  flavonoid also appeared to reduce the RV-triggered immune system  response that can cause cytokines (proteins that are secreted by  specific cells of the immune system) to induce excess inflammation. "Therefore,  quercetin may be beneficial in the treatment of viral infections,  particularly in patients with underlying chronic lung disease,"  the researchers stated.