To Live in Mud: Disease Mechanisms and Treatment of Cystic Fibrosis
Affecting over 30,000 individuals in the United States alone, cystic fibrosis is a disease that may alter and taint one’s daily experiences, causing one to drown in dense hazes of frequent treatment, prolonged suffering, and obtain a unique perspective on the concept of life. Cystic fibrosis obtains widespread effects on the body systems, an etiology of genetic inheritance, severe signs and symptoms, and a multitude of diagnostic tests and treatments.
“Cystic Fibrosis: MedlinePlus Medical Encyclopedia.” Medlineplus.gov, 2018, medlineplus.gov/ ency/article/000107.htm. Accessed 10 Mar. 2023.
Cystic fibrosis involves thick, salty secretions of mucus causing respiratory, digestive, reproductive, and other body systems complications. The buildup of abnormal mucus in the lungs is particularly dangerous as the increased susceptibility to frequent bacterial and fungal infections of the lungs is paired with an immunocompromised response due to the damage to mucosal immunity. The warm, moist environment of the mucus accommodates a variety of pathogens in the lungs of cystic fibrosis patients, including Pseudomonas aeruginosa, Burkholderia cepacia complex, Methicillin-resistant Staphylococcus aureus, and the Aspergillus species which secrete exotoxins and may lead to pneumonia, septicemia, sinus infections, or bronchitis. Moreover, these frequent pathogenic infections may result in the deterioration of the lungs and impair their function. Another complication affecting the lungs in cystic fibrosis patients is the permanent deformity of the bronchial tubes known as bronchiectasis. This reshaping occurs when the mucus forces the bronchial tubes to expand and scar, ultimately creating challenges in pulmonary ventilation and the clearing of mucus from the airways. If bronchiectasis is adjacent to blood vessels, individuals may face hemoptysis, the coughing up of blood which even in minimal amounts may prove to be hazardous. Finally, if air collects in the pleural cavity it may place pressure on the lungs, heart, and blood vessels and may even lead to the partial or complete collapse of the lungs called pneumothorax. Overall, the thick mucus of the lungs may lead to a variety of life-threatening diseases, both directly and indirectly, including chronic pathogen invasion, bronchiectasis, hemoptysis, and pneumothorax.
“What Is Cystic Fibrosis?” NHLBI, NIH, 24 Mar. 2022, www.nhlbi.nih.gov/health/cystic-fibrosis. Accessed 10 Mar. 2023.
The digestive system is also greatly impacted by cystic fibrosis, even from birth. In fact, around 10 to 15 percent of patients develop meconium ileus in which the first, dark fecal matter of an infant is sticky due to the obstruction of the intestines from the buildup of thick mucus. This is often accompanied by abdominal swelling and vomiting. However, even more concerning is how the mucus may block the pancreatic duct, whose primary function is to secrete pancreatic enzymes that aid in the chemical breakdown of chyme from the stomach in the small intestine. In a person with cystic fibrosis, the thickened mucus in the pancreas may even cause scarring to occur, further preventing the complete breakdown to occur, known as pancreatic insufficiency. The undigested matter may be excreted in the feces, and the complications while digesting may result in malnutrition, stunted growth, and either increased or lack of appetite. A similar blockage and inflammation may occur in the common bile duct leading to numerous liver diseases such as cirrhosis, jaundice, steatohepatitis, or cholelithiasis. Furthermore, the lesions in the pancreatic cells may foster an increased chance of Type I or insulin-dependent diabetes. Infertility in men due to the occlusion or absence of the vas deferens and seminal vesicles as well as decreased fertility in women is also exhibited in many cystic fibrosis patients.
Cystic fibrosis is a congenital disease caused by point mutations at locus chromosome 7 in the CFTR gene. This gene encodes for cystic fibrosis transmembrane conductance regulators which help in the dismissal of chloride from mucus and sweat as well as water through the process of osmoregulation. However, if an individual carries two copies of these mutations, meaning they are homozygous, the protein regulator will not be expressed leading to increased chloride levels and the perseverance of water in the mucus and sweat causing thickened, salty attributes. Though homozygous individuals for these mutations may suffer severe complications, as aforementioned, heterozygous carriers of the mutation of cystic fibrosis have been associated with increased survival from cholera and dehydration, due to higher water retention, without the expression of adverse effects associated with cystic fibrosis. Hence, due to the process of natural selection, a mutation and a single chromosome may have been favorable and could explain the prevalence of this mutation in people of northern European descent as cholera plagued many towns during the 1800s.
Some signs of cystic fibrosis include frequent respiratory infections, clubbing of fingers and toes, nasal polyps, and increased chloride levels in sweat and mucus while symptoms include wheezing, shortness of breath, abdominal pain, difficulty in physical exertion, and large movements of foul-smelling fecal matter. Diagnostic tests for cystic fibrosis begin soon after birth since infants are screened for abnormally high levels of immunoreactive trypsinogen. Though this test may be strong evidence an individual has cystic fibrosis, other diagnostic tests must be run such as a sweat test. During a sweat test, sweat is inspected for increased levels of sodium and chloride.
Currently, there is no cure for cystic fibrosis; however several kinds of treatment options have been established to minimize effects and increase the quality of life and life expectancy. Chest physical therapy is often performed to loosen mucus for the chest and allow clearer breathing. However, these techniques must be executed frequently as it only establishes temporary relief. Medications that are used for cystic fibrosis include hypertonic saline to thin the mucus, antibiotics preventing bacterial infection of the lungs, anti-inflammatory and bronchodilators drugs to decrease swelling and open the airways, and oral pancreatic enzymes to aid in the absorption and chemical breakdown of nutrients. More recent treatment options involve medication that targets the CFTR gene to improve the function of the cystic fibrosis transmembrane conductance regulators. Finally, surgeries may be performed to treat any damaged organ or body system affected by cystic fibrosis such as noninvasive ventilation, feeding tubes, bowel surgery, or even lung or liver transplantation.
L. Norsa, et al. “Night Blindness in Cystic Fibrosis: The Key Role of Vitamin a in the Digestive System.” Nutrients, 2019, www.semanticscholar.org/paper/Night-Blindness-in-Cystic-Fibrosis%3A-The-Key-Role-of-Norsa-Zazzeron/ff01231cd3b21053fa7fd5033c52904574e889af. Accessed 10 Mar. 2023.
Overall, cystic fibrosis has various adverse effects on the lungs, digestive tract, and reproduction derived from the inheritance of two copies of a mutation in the CFTR gene. It is characterized by several severe signs and symptoms which, along with diagnostic tests such as the sweat test, help to determine if a patient presents with cystic fibrosis. Medical treatment and surgical intervention have been used to relieve some of the signs and symptoms and increase life expectancy; however, a cure for this genetic disease is still not available. This encourages further research into cystic fibrosis in order to find ways to permanently eliminate the effects of a life-rattling disease. Perhaps, this could be accomplished through CRISPR/Cas9 to reverse the changes in the nucleotide bases. However, awareness is the first step to change. By developing a sense of empathy and understanding and contributing in our own way to help overcome the challenges faced during cystic fibrosis, perhaps a cure will appear in the near future.
References
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“Cystic Fibrosis - Symptoms and Causes.” Mayo Clinic, 2021, www.mayoclinic.org/diseases-conditions/cystic-fibrosis/symptoms-causes/syc-20353700#:~:text=Cystic%20fibrosis%20is%20one%20of,mucus%20from%20the%20bronchial%20tubes. Accessed 26 Feb. 2023.
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Steefel, Lorraine. "Pneumothorax." The Gale Encyclopedia of Medicine, edited by Jacqueline L. Longe, 6th ed., vol. 7, Gale, 2020, pp. 4104-4105. Gale In Context: Science, link.gale.com/apps/doc/CX7986601489/GPS?u=tlc201825818&sid=bookmark-GPS&xid=6fe523e7. Accessed 25 Feb. 2023.
