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Airway Remodeling in Asthma

Why Asthma Control Is Crucial

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Updated: March 18, 2008

Airway remodeling in asthma is what happens in response to long-term, unresolved airway inflammation. When airway inflammation is not adequately treated, it can result in permanent structural changes in the airways. Airway remodeling is the strongest argument for asthma control.

Asthma is known to be a chronic disease for which there is currently no cure. It involves inflammation of your airways in response to being exposed to certain asthma triggers, such as pollen or tobacco smoke. Each person's triggers may be different. But when the airways are inflamed, asthma symptoms such as wheezing, coughing, chest tightness and shortness of breath make breathing difficult.

Most of the time, these changes in the airways, as well as the resulting symptoms, can be prevented with daily controller medicines or reversed temporarily when controller medicines fail to stop a reaction. But in some people, especially people who have severe persistent asthma, medication may not provide adequate asthma control.

In these cases, a certain degree of airway inflammation is always present. Over time, the body tries to fix this inflammation by triggering changes in the repair function of the lining of the airways. Experts are not sure about exactly what happens to the repair function, but they do know that the following structural changes in the airway occur as a result:

  • Increased airway wall thickness that involves both smooth muscle and collagen tissue
  • Increased mucous glands and mucus production
  • Increased vascularity, or blood supply, in the airways

Unfortunately, these structural changes – once they occur – are lasting and will lead to reduced lung function, with a loss of ability to move air into and out of the lungs.

Which Comes First?

We know that people who have severe asthma are the ones most likely to have airway remodeling. What we don't know is if the airway remodeling is a result of the severe persistent asthma, or if asthma is more severe and less responsive to treatment in certain people because of the airway remodeling.

However, the link between underlying inflammation and airway changes is clear. Studies have also shown that being exposed to allergens on an ongoing basis can lead to more smooth muscle in airways, as well as increasing the amount of mucus produced.

Who Is at Risk?

Certainly, people with severe asthma are at risk for airway remodeling. In addition, some studies suggest that the longer you have asthma, the more at risk you are. Also, the younger a person is when he first develops asthma may increase risk. This is especially true if the child has persistent symptoms and a history of airway obstruction. It is possible that there is also a complex link between:

  • Genetic predisposition
  • Environmental factors
  • Changes in the immune response

There is still a lot to learn, though, about causative factors with airway remodeling. Further study is needed to get better, more reliable answers.

Most Important Facts

One thing is already clear, however. Environment – and exposure to allergens – plays a significant role in the development of airway remodeling. Continous, or repeated, exposure to allergens will lead to an increased number and frequency of asthma flares or asthma attacks. That sets the stage for airway remodeling as well.

The bottom line is that effective treatment of your asthma aimed at complete asthma control is crucial in preventing airway remodeling. The first step is to do everything you can to avoid your known triggers.

Also, if you are still having symptoms frequently, even when taking asthma medicine, then it's time to talk with your doctor about modifying your asthma treatment plan.

If you are not taking an inhaled steroid, that's the first step. If you are taking a steroid already, then you may need to add a long-acting beta agonist to the mix for better control. An immunomodulator such as Xolair may also be a viable alternative.

Sources:

Hahn, Eugenia, Iftikhar Hussain. "Airway Remodeling: Why taking care of asthma is important." Allergy & Asthma Advocate. Fall 2005. <http://www.aaaai.org/patients/advocate/2005/fall/remodeling.asp>

Hahn, EugeniaElias, Jack, Zhou Zhu, Geoffrey Chupp, Robert J. Homer. "Airway remodeling in asthma." J Clin Invest.. 1999 October 15; 104(8). <http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=10525034>

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