Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a major, global health problem and has only begun to be studied to a significant extent within the past two decades. Projections indicate that COPD may become the third most common cause of death and fifth most common cause of disability worldwide by 2020 (Burney et al, 2014). COPD is characterized by irreversible damage, obstruction, and infiltration of bronchioles and lung parenchyma, causing airflow limitation in patients.

BCM441 - COPD figure 2
Figure 1 – Comparison of normal lung tissue vs that of a COPD patient. (Source – Google Images)

The immune system is responsible for fighting infection and cleaning up the body in response to physiological stresses. “Inflammation” refers to the immune system’s response to these harmful stimuli (infection, pathogens, damage, irritants). Some cells involved in the inflammatory process include neutrophils, macrophages, T-cells, and eosinophils, among others. In summary, in response to an infection or in the presence of irritants, these cells can release factors that can fight off the pathogens and neutralize the irritants in order to protect the body.

Neutrophils, as an example, release several proteases during the inflammatory response. While these can help fight against things like bacterial infection, they can act on many kinds of proteins in close proximity. In the case of COPD, some of these proteases can break down proteins located in lung parenchyma and/or bronchioles, causing damage to the lungs. In addition, some inflammatory cells can release reactive oxygen species (ROS) as a defense mechanism. These ROS can also damage lung tissue (in addition to their normal and beneficial inflammatory effects).

BCM441 - COPD figure 3
Figure 2 – Effects of immune system cells on lungs. Forgetting about specifics, note the harmful effects the immune system can have on lung tissue. (Source – Google Images)

Cigarette smoking is currently the most significant risk factor (by far) for COPD. Cigarette smoke creates many irritants that, when inhaled, can trigger inflammation in the lungs, recruiting the cells noted previously (neutrophils, macrophages, T-cells, eosinophils), which can secondarily cause irreversible lung damage, resulting in COPD. The same effects can occur with exposure to air pollution and even viral infections such as adenovirus (Morimoto et al, 2009). The presence of these irritants also recruits more inflammatory cells, which themselves can obstruct bronchioles.

Luckily, we have a way of protecting our lung tissue from possible damage from ROS and proteases, in the form of anti-oxidants and anti-proteases, such as α1‐antitrypsin. However, this also means that individuals with α1‐antitrypsin deficiency are at an increased risk for COPD. In contrast to external risk factors (cigarette smoking, pollution, respiratory infection), α1‐antitrypsin deficiency is currently the only known host risk factor (Barnes et al, 2003).

Currently, there is no known and proven treatment for COPD. The lung tissue damage by these proteases and ROS is irreversible, and the narrowing of airways is also untreatable at this time. Unlike asthma, steroids do not offer relief of symptoms in COPD.

7 Replies to “Chronic Obstructive Pulmonary Disease (COPD)”

  1. Really nice job, this article was extremely informative. It was really nice to have the links to the definitions for some of the scientific terms that aren’t something that is commonly known. Two other words that I would also possibly define are, eosinophils and α1‐antitrypsin. Great job providing an example and describing the leading risk factor, are there any other risk factors that people should be aware of? Also are there any other preventive measures that can be taken against this disease besides what our body naturally does? Lastly I would include the part about the other external risk factors in second to last paragraph, in the paragraph above it. It would fit better into that section since that seems to be more focused on external risk factors than the current paragraph it is in does. Overall this is a really great informative article on COPD!

  2. Very accessible to the lay reader. Cause and effect are related clearly, using scientific terminology when needed, but maintaining clarity for the non-science reader by using conversational but authoritative tone and everyday vocabulary.

  3. This article is very informative to the reader and the author did a nice job in informing the reader of the cause (s) and effects of COPD. Specifically, as a lay person I came to know from reading this article that COPD is not only caused by contracted infection but also by environmental irritants including but not limited to inhaling cigarettes. The fact that the author relayed this direct information made me think about being so very cautious of being around any kind of chemical that could irritate the lungs. The author also made it clear that the effects of the irritants are not reversible sending a clear message that inflammation of the lungs is not only very serious but can (in many circumstances) be consciously avoidable. The article also made me even more away that we can help prevent lung tissue damage by intaking more anti oxidants which again is another conscious decision we can make in keeping our lungs healthy. I would recommend that the author more simplify this information for elementary and secondary school readers and get this important message out to our youth. Great Job!

    1. Thanks for your comment! I’m glad you could reach this information, it’s definitely worth knowing, as COPD is one of the leading causes of death and disability. I do think, however, that the current research is really pinning cigarette smoking as the main cause, so as long as we keep ourselves and our children smoke-free, we can avoid many cases of COPD. In terms of simplifying the information, I had the intent of creating this page for an older audience (high school years and beyond) without a scientific background, and I do understand that it would be difficult for those in elementary & middle school to grasp. Perhaps this blog can incorporate a separate page for an even younger audience in the future? I like that idea!

  4. This article was highly understandable, aside from some science terms I do not recognize. Is there a definition for ROS ? It is a bit confusing that you say it has both damaging and beneficial effects. Good job Besher

    1. You bring up a fair point, maybe I will re-word it in order to clear up this possible source of confusion. Reactive oxygen species can damage fats, proteins, and/or DNA. This is beneficial, because these inflammatory cells can damage the proteins/DNA of an infectious bacteria and kill it, so that we can live infection-free.

      However, if uncontrolled, these ROS can damage our own proteins and DNA – and this can cause COPD when it occurs in the lungs.

      Think about training in martial arts – with this training, you can defend yourself against an attacker, which is great. However, this training can also equip someone to be a potent attacker, so this individual needs some control. Similarly, ROS can kill bacteria and keep us safe, but they need to be controlled or they can wreak havoc on our bodies.

      Lastly, there actually is a definition of ROS on the primer page, and I’ve added the links. Thanks again for your input!

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