THE MYSTERY OF ASTHMA:
Understanding a Common but Heterogeneous Disease
Editor's Note: Nadia G. wrote this essay, summarizing her work Science Research, for the Dupoint Essay Competition.
A young girl packs her soccer bag. Cleats, shin guards, socks, and a water bottle get zipped up inside. At the last minute, she remembers her asthma inhaler and shoves it in a side pocket. Later, as she warms up with a light jog around the field, her heart rate picks up and her breath comes with difficulty, wheezing slightly as the air squeezes in and out of her lungs (“What is Asthma,” 2014). She is wary of her labored breathing, monitoring it, always fearing that playing the sport she loves will bring on an attack.
What if there existed a future in which children like this girl didn’t have to panic each time they ran and played? What if, at a young age, a child could receive a predictive genetic test to identify gene mutations, a diagnosis could be anticipated, and a child could begin treatment for asthma before experiencing symptoms, helping to prevent a constant wariness of attacks later in life (“How are Genetic,” 2015)? This type of treatment does not yet exist, but with a continuous increase in research concerning the genetic components of asthma and possible treatments, this scenario could be a viable option in the future (“What are the Types,” 2015).
Asthma is a disease that affects close to twenty-five million people in the United States today and is the most prevalent chronic condition among children (Doeing & Solway, 2013). It is responsible for over thirteen million total missed days of school and ten million missed days of work for Americans each year (“Asthma and Allergy”). For such a common and disruptive disease, one would correctly assume that large-scale research is being conducted. There are numerous short and long term medicines available, but as of yet, asthma has no cure (“What is Asthma,” 2014). Scientists are faced with the challenge of understanding and countering a heterogeneous disease, meaning asthma is individual to each patient and is caused by many different factors, both environmental and genetic (Phimister & Levy, 2013). Asthma is generally associated with chest tightness, wheezing, and coughing due to a restriction of airflow through the respiratory tract (Doeing & Solway, 2013). These symptoms are caused by airflow obstruction, inflammation, and hyperresponsiveness in the airway that occur at varying levels of severity from patient to patient (Phimister & Levy, 2013). Currently, treatments range from long-term control medications taken daily, which include anti-inflammatory drugs, muscle relaxants, and beta agonists that keep the airways open, to rescue medications such as the quick-relief inhalers commonly carried by asthma patients to stop attacks (“Agonist,” 2012; Mayo Clinic Staff, 2014). These medications lessen asthma symptoms but don’t completely eradicate them (Mayo Clinic Staff, 2014). However, as more research is done, scientists are increasingly emphasizing the effects of genes associated with asthma. In doing so, they hope to target the disease closer to its source (Phimister & Levy, 2013). By identifying the genes associated with asthma, understanding why they make individuals prone to asthmatic symptoms, and finding a way to counteract the negative effects of these genes, scientists have the potential to dramatically lessen symptoms for millions of asthma patients.
One such gene is known as ORMDL3. Located on the seventeenth chromosome, ORMDL3 plays an important role in people with asthma for two reasons (“Genes and Mapped Phenotypes”, 2015). The first is that ORMDL3 is over expressed in asthmatic patients (Phimister & Levy, 2013). This difference in expression between people with and without asthma suggests that this change is significant and possibly that ORMDL3 plays a role in causing asthma. Secondly, ORMDL3 has been linked to airway hyperresponsiveness, one of the markers of asthma, by its role in airway smooth muscle cells (Phimister & Levy, 2013).
Airway smooth muscle surrounds the respiratory tract (Doeing & Solway, 2013). It is an involuntary muscle; instead of being controlled consciously as in the way a person opens and closes their hand, smooth muscles contract without conscious control, similarly to the way the brain controls the beating of the heart. Normally, airway smooth muscle is meant to protect a person from inhaling dangerous substances. When an irritating foreign substance is detected by the windpipe walls, the airway smooth muscle contracts, thus narrowing the airway and preventing too much of the harmful matter from entering the lungs (Doeing & Solway, 2013). In patients with asthma, the airway smooth muscle contracts excessively, stays contracted for longer periods of time, and contracts harder, resulting in too little air reaching the lungs and difficulty breathing (Doeing & Solway, 2013). This over reaction in the airway smooth muscle is a result of disrupted levels of lipids within the individual smooth muscle cells (Phimister & Levy, 2013).
ORMDL3 is responsible for the regulation of these lipids (Gault, 2010). When the gene is over expressed in individuals with asthma, levels of lipids become unbalanced in the airway smooth muscle cells, causing airway hyperreactivity (Phimister & Levy, 2013). If a drug was found that could restore balance within these airway smooth muscle cells, counteracting the effects of over expression of ORMDL3, then airway hyperreactivity would be reduced in a large portion of asthmatic patients and the result would be less strong and harmful asthma symptoms. Two drugs are currently being tested in preclinical studies (Worgall). The first, GlyH-101, is currently used to treat cystic fibrosis, and the second, fenretinide, is used in the treatment of some types of cancerous tumors (“CFTR Inhibitor,” 2015; “Definition of Fenretinide”). Both drugs have been found to balance the lipid levels in airway smooth muscle cells and counteract the negative effects of ORMDL3 over expression (Worgall). Because both drugs have known safety in humans, they will hopefully pass quickly into clinical trials for human patients with asthma.
These drugs could be another important advancement in solving the puzzle that is asthma. Patients taking either of these drugs would gain long-term benefits and be able to live their lives with less worry about asthma symptoms and attacks (Phimister & Levy, 2013). These drugs would hopefully reduce the number of missed days of work, school, and athletics for asthma patients in the United States and around the world. However, asthma is still far from being “cured”. These drugs would only fill in another gap in the treatment of and knowledge about asthma. But it is these individual advancements that when understood together will lead to a larger and hopefully one day complete knowledge of asthma. Until then, advancements like this one will help patients struggling with asthma live their daily lives with more normality and security.
What if there existed a future in which children like this girl didn’t have to panic each time they ran and played? What if, at a young age, a child could receive a predictive genetic test to identify gene mutations, a diagnosis could be anticipated, and a child could begin treatment for asthma before experiencing symptoms, helping to prevent a constant wariness of attacks later in life (“How are Genetic,” 2015)? This type of treatment does not yet exist, but with a continuous increase in research concerning the genetic components of asthma and possible treatments, this scenario could be a viable option in the future (“What are the Types,” 2015).
Asthma is a disease that affects close to twenty-five million people in the United States today and is the most prevalent chronic condition among children (Doeing & Solway, 2013). It is responsible for over thirteen million total missed days of school and ten million missed days of work for Americans each year (“Asthma and Allergy”). For such a common and disruptive disease, one would correctly assume that large-scale research is being conducted. There are numerous short and long term medicines available, but as of yet, asthma has no cure (“What is Asthma,” 2014). Scientists are faced with the challenge of understanding and countering a heterogeneous disease, meaning asthma is individual to each patient and is caused by many different factors, both environmental and genetic (Phimister & Levy, 2013). Asthma is generally associated with chest tightness, wheezing, and coughing due to a restriction of airflow through the respiratory tract (Doeing & Solway, 2013). These symptoms are caused by airflow obstruction, inflammation, and hyperresponsiveness in the airway that occur at varying levels of severity from patient to patient (Phimister & Levy, 2013). Currently, treatments range from long-term control medications taken daily, which include anti-inflammatory drugs, muscle relaxants, and beta agonists that keep the airways open, to rescue medications such as the quick-relief inhalers commonly carried by asthma patients to stop attacks (“Agonist,” 2012; Mayo Clinic Staff, 2014). These medications lessen asthma symptoms but don’t completely eradicate them (Mayo Clinic Staff, 2014). However, as more research is done, scientists are increasingly emphasizing the effects of genes associated with asthma. In doing so, they hope to target the disease closer to its source (Phimister & Levy, 2013). By identifying the genes associated with asthma, understanding why they make individuals prone to asthmatic symptoms, and finding a way to counteract the negative effects of these genes, scientists have the potential to dramatically lessen symptoms for millions of asthma patients.
One such gene is known as ORMDL3. Located on the seventeenth chromosome, ORMDL3 plays an important role in people with asthma for two reasons (“Genes and Mapped Phenotypes”, 2015). The first is that ORMDL3 is over expressed in asthmatic patients (Phimister & Levy, 2013). This difference in expression between people with and without asthma suggests that this change is significant and possibly that ORMDL3 plays a role in causing asthma. Secondly, ORMDL3 has been linked to airway hyperresponsiveness, one of the markers of asthma, by its role in airway smooth muscle cells (Phimister & Levy, 2013).
Airway smooth muscle surrounds the respiratory tract (Doeing & Solway, 2013). It is an involuntary muscle; instead of being controlled consciously as in the way a person opens and closes their hand, smooth muscles contract without conscious control, similarly to the way the brain controls the beating of the heart. Normally, airway smooth muscle is meant to protect a person from inhaling dangerous substances. When an irritating foreign substance is detected by the windpipe walls, the airway smooth muscle contracts, thus narrowing the airway and preventing too much of the harmful matter from entering the lungs (Doeing & Solway, 2013). In patients with asthma, the airway smooth muscle contracts excessively, stays contracted for longer periods of time, and contracts harder, resulting in too little air reaching the lungs and difficulty breathing (Doeing & Solway, 2013). This over reaction in the airway smooth muscle is a result of disrupted levels of lipids within the individual smooth muscle cells (Phimister & Levy, 2013).
ORMDL3 is responsible for the regulation of these lipids (Gault, 2010). When the gene is over expressed in individuals with asthma, levels of lipids become unbalanced in the airway smooth muscle cells, causing airway hyperreactivity (Phimister & Levy, 2013). If a drug was found that could restore balance within these airway smooth muscle cells, counteracting the effects of over expression of ORMDL3, then airway hyperreactivity would be reduced in a large portion of asthmatic patients and the result would be less strong and harmful asthma symptoms. Two drugs are currently being tested in preclinical studies (Worgall). The first, GlyH-101, is currently used to treat cystic fibrosis, and the second, fenretinide, is used in the treatment of some types of cancerous tumors (“CFTR Inhibitor,” 2015; “Definition of Fenretinide”). Both drugs have been found to balance the lipid levels in airway smooth muscle cells and counteract the negative effects of ORMDL3 over expression (Worgall). Because both drugs have known safety in humans, they will hopefully pass quickly into clinical trials for human patients with asthma.
These drugs could be another important advancement in solving the puzzle that is asthma. Patients taking either of these drugs would gain long-term benefits and be able to live their lives with less worry about asthma symptoms and attacks (Phimister & Levy, 2013). These drugs would hopefully reduce the number of missed days of work, school, and athletics for asthma patients in the United States and around the world. However, asthma is still far from being “cured”. These drugs would only fill in another gap in the treatment of and knowledge about asthma. But it is these individual advancements that when understood together will lead to a larger and hopefully one day complete knowledge of asthma. Until then, advancements like this one will help patients struggling with asthma live their daily lives with more normality and security.
Agonist. (2012, March 19). Retrieved January 10, 2015, from http://www.medicinenet.com/script/main/art.asp?articlekey=7835
Asthma and Allergy Foundation of America - Information About Asthma, Allergies, Food Allergies and More!. Retrieved January 10, 2015, from https://www.aafa.org/display.cfm?sub=42&id=8
CFTR Inhibitor II, GlyH-101 (CAS 328541-79-3 ). (2015). Retrieved January 10, 2015, from http://www.scbt.com/datasheet-221418-cftr-inhibitor-ii-glyh-101.html
Definition of fenretinide - National Cancer Institute Drug Dictionary. Retrieved January 10, 2015, from http://www.cancer.gov/drugdictionary?cdrid=39582
Doeing DC, Solway J. Airway smooth muscle in the pathophysiology and treatment of asthma. J Appl Physiol 114: 834-843. 2013.
Gault, C. R. (2010). An overview of sphingolipid metabolism: From synthesis to breakdown. NIH Public Access. Retrieved November 24, 2014.
Genes and mapped phenotypes. (2015, January 8). Retrieved January 10, 2015, from http://www.ncbi.nlm.nih.gov/gene/94103
Hannun, Y. A., & Obeid, L. M. (2008). Principles of bioactive lipid signaling: lessons from sphingolipids[Review of articles Multiple]. Nature Reviews, 9, 139-150.
How are genetic conditions diagnosed? (2015, January 12). Retrieved January 14, 2015, from http://ghr.nlm.nih.gov/handbook/consult/diagnosis
Koppelman, G. H., Te Meerman, G. J., & Postma, D. S. (2008, September). Result Filters. Retrieved January 14, 2015, from http://www.ncbi.nlm.nih.gov/pubmed/18757702
Mayo Clinic Staff. (2014, February 13). Asthma. Retrieved January 10, 2015, from http://www.mayoclinic.org/diseases-conditions/asthma/basics/treatment/con-20026992
Phimister, E. G., & Levy, B. D. (2013). Sphingolipids and Susceptibility to Asthma. New England Journal of Medicine, 369(10), 976-978. doi: 10.1056/NEJMcibr1306864
What are the types of genetic tests? (2015, January 12). Retrieved January 14, 2015, from http://ghr.nlm.nih.gov/handbook/testing/uses
What Is Asthma? (2014, August 4). Retrieved January 10, 2015, from http://www.nhlbi.nih.gov/health/health-topics/topics/asthma
Worgall, S. [Grant proposal for sphingolipid experiments]. New York, NY.
Worgall, T. S., Veerappan, A., Sung, B., Kim, B. I., Weiner, E., Bholah, R., . . . Worgall, S. (2013). Impaired Sphingolipid Synthesis in the Respiratory Tract Induces Airway Hyperreactivity. Science Translational Medicine, 5(186), 186ra67-186ra67. doi:10.1126/scitranslmed.3005765
Asthma and Allergy Foundation of America - Information About Asthma, Allergies, Food Allergies and More!. Retrieved January 10, 2015, from https://www.aafa.org/display.cfm?sub=42&id=8
CFTR Inhibitor II, GlyH-101 (CAS 328541-79-3 ). (2015). Retrieved January 10, 2015, from http://www.scbt.com/datasheet-221418-cftr-inhibitor-ii-glyh-101.html
Definition of fenretinide - National Cancer Institute Drug Dictionary. Retrieved January 10, 2015, from http://www.cancer.gov/drugdictionary?cdrid=39582
Doeing DC, Solway J. Airway smooth muscle in the pathophysiology and treatment of asthma. J Appl Physiol 114: 834-843. 2013.
Gault, C. R. (2010). An overview of sphingolipid metabolism: From synthesis to breakdown. NIH Public Access. Retrieved November 24, 2014.
Genes and mapped phenotypes. (2015, January 8). Retrieved January 10, 2015, from http://www.ncbi.nlm.nih.gov/gene/94103
Hannun, Y. A., & Obeid, L. M. (2008). Principles of bioactive lipid signaling: lessons from sphingolipids[Review of articles Multiple]. Nature Reviews, 9, 139-150.
How are genetic conditions diagnosed? (2015, January 12). Retrieved January 14, 2015, from http://ghr.nlm.nih.gov/handbook/consult/diagnosis
Koppelman, G. H., Te Meerman, G. J., & Postma, D. S. (2008, September). Result Filters. Retrieved January 14, 2015, from http://www.ncbi.nlm.nih.gov/pubmed/18757702
Mayo Clinic Staff. (2014, February 13). Asthma. Retrieved January 10, 2015, from http://www.mayoclinic.org/diseases-conditions/asthma/basics/treatment/con-20026992
Phimister, E. G., & Levy, B. D. (2013). Sphingolipids and Susceptibility to Asthma. New England Journal of Medicine, 369(10), 976-978. doi: 10.1056/NEJMcibr1306864
What are the types of genetic tests? (2015, January 12). Retrieved January 14, 2015, from http://ghr.nlm.nih.gov/handbook/testing/uses
What Is Asthma? (2014, August 4). Retrieved January 10, 2015, from http://www.nhlbi.nih.gov/health/health-topics/topics/asthma
Worgall, S. [Grant proposal for sphingolipid experiments]. New York, NY.
Worgall, T. S., Veerappan, A., Sung, B., Kim, B. I., Weiner, E., Bholah, R., . . . Worgall, S. (2013). Impaired Sphingolipid Synthesis in the Respiratory Tract Induces Airway Hyperreactivity. Science Translational Medicine, 5(186), 186ra67-186ra67. doi:10.1126/scitranslmed.3005765
