Asthma: Characteristics, Treatment Approaches, and Genomic Issues

Pathophysiology and Age Continuum for Asthma

Asthma is a chronic inflammatory disorder of the airways characterized by underlying inflammation, airflow obstruction, bronchial hyperresponsiveness, and recurring symptoms. Moreover, asthma depends on many environmental factors. In particular, asthma is caused by many airway changes involving bronchoconstriction, airway edema, airway remodeling, and airway hyper-responsiveness. It is critical to notice that inflammation is central to asthma pathophysiology. It is significant to understand that airway inflammation can engage in many multiple mediators and cell types’ interaction with the airways. As a result, it provokes such disease pathophysiological features as breath shortness, wheezing, airflow limitation and bronchial inflammation that lead to cough episodes. Despite asthma’s distinct phenotypes, airway inflammation remains a consistent pattern. However, the airway inflammation pattern in asthma does not necessarily have to depend on disease duration, persistence and severity. One of the strongest asthma phenotype determinants of the asthma phenotype in childhood is age. The difference between age groups is critical for management strategies and diagnostics. In general, there are such age groups as infants (0-2), preschool children (3-5), school children (6-12), adolescents and adults. Among infants, the severity of the symptoms is the main severity indicator. It is critical to notice whether the child was wheezing most of the time during the three months. In the case of preschool children, asthma can be diagnosed if symptoms disappear between episodes and a cold follows. In this age group, viruses- and allergen-included asthma is often met. Children’s situation is quite similar for school age, but allergen-included asthma is more common. Adolescents can experience nonatopic asthma, and some habits, like smoking, can provoke the disease. Therefore, age is highly critical in understanding asthma.

Genomic Issues of Asthma

Asthma determinants can be lifestyle and environment, as the disorder triggers and modifiers, infection, tobacco smoke, pollutants, irritants, exercise, weather, nutrition, stress and concurrent triggers. At the same time, the asthma determinant can be genes. The impact of genetic variants of asthma and asthma-related phenotypes play a great role in heterogeneity and can be seriously impacted by several environmental factors. Therefore, many children that have asthma do not have parents with asthma, while many parents with asthma have children without the disease. It is common knowledge that environmental and inherited factors impact the risk of asthma development. Many types of research were devoted to the genomic and genetic studies of asthma, particularly severe asthma. Approximately 5% of children with this disorder suffer from chronic symptoms, despite the treatments that include various drugs. The results showed that severe asthma often continues into adulthood, and no single gene was found that can explain the main causes of asthma. Only in recent times research started to focus on these issues. In general, gene expression is one of the many mechanisms that can impact the protein level and its effect on cellular functions. Therefore, variation in gene expression is highly critical for normal cellular events, just as for the processes that are related to the disorder’s development. Asthma is considered one of the most widespread disorders among children in the developed nation because its rate increased worldwide within the last decades. Hence, it is an extremely specific and complex disorder with environmental and genetic risk factors. In general, asthma is provoked by “multiple interacting genes, some having protective effects and others contributing to the disease pathogenesis where every gene had own tendency to be impacted by the environment”. The approaches that were used for asthma gene discovery evolved over time because different genotyping technologies become more accessible and less costly. Since the 21st century, applied technologies have helped handle many gene discovery limitations. According to the candidate gene association studies, the most common approach is the case-control study, while alternative approaches are cross-sectional and cohort study designs in which people are chosen based on the disease status base. Most of the genetic asthma studies were candidate gene association researched, where genes are chosen based on their strong engagement in the pathogenesis. Hence, mentioned studies are strongly biased to research about the “immune-related genes”. In particular, the greatest area for improvement of this research is its limitation of what people know or think is known about gene functions and disease pathogenesis. Thus, the candidate gene approach alone cannot discover novel genes or pathways. In contrast, to candidate gene association research, another approach regarding gene discovery is genome-wide, which covers all of the genome regions. Therefore, this approach is considered hypothesis-generated or hypothesis-free. The best positive side of the genome-wide approach is its ability to explore the novel pathways and genes involved in disorder pathogenesis. Nonetheless, the main weakness of these approaches is the statistical burden caused by the large quantity of performed tests and the need for big sample sizes to gain statistical significance. Additionally, the connection between gained variants and disorder pathogenesis can sometimes be unclear. The next issue is genome-wide linkage studies. The main strengths of this approach are that linkage studies require genetic markers and present the same or even better information and coverage. Another positive side is that this research will reveal genes or regions “that harbor multiple rare variants that confer risk for the disorder, even if the specific variants differ among families”. However, limitations are the studying families’ presence need and that this approach identifies broad results, which can include many genes and “has low power to detect risk variants with modest effect sizes on disorder risk”. The other approach is genome-wide association studies (GWAS). The main strength of this approach is its “excellent resolution, power to detect risk variants with modest effect sizes, and absence of the studying families’ requirement”. The main weakness of this approach is that it, in the first turn, identifies the common risk possibilities due to the most common variants’ involvement by the genotyping platforms. The next matter is the re-sequencing studies. This approach is based on the position that “rare variants with larger effect sizes on disorder risk than common variants will explain the significant portion of the genetic risk for common disorders”. Nowadays, this is one of the most dominating approaches. Therefore, these approaches have helped to gain crucial information regarding genes’ role in asthma. For instance, based on the candidate gene association studies, it was found that variations of more than thirty genes were associated with asthma. In the case of linkage studies, it was stated that nine genes were identified from 1996 to 2009 and were novel. At the same time, many other studies were conducted to research the relation of genes to asthma disorder. However, more information should be devoted to the effects of the associated variation on the gene function or regulation of the associated genes in asthma pathogenesis.

Literature Review

Research and guidelines were devoted to the asthma disorder among children and adults. In this paper, several types of research were analyzed to identify the asthma diagnosis treatment and the main gaps and health care delivery. Therefore, the paper analyzed studies conducted seven years ago. In general, such databases as NCBI, The Journal of Allergy and Clinical Immunology, the Journal of the Canadian Thoracic Society and the Journal of Emergency Medicine were used. For the keywords as asthma, treatment, diagnosis, research, genes, and pathophysiology were used. Gained information was collected based on the logical approach. First of all, the analyzed papers were about asthma in general, its diagnosis and the related issues, and there were analyzed guidelines and papers regarding treatment approaches. Ahmad, Ismail, and Sulong stated that asthma is a chronic respiratory disorder prevalent worldwide, especially among children and some minority groups. The research provided a literature review to summarize the existing reviews on asthma interventions that community asthma control programs can support. Therefore, in the research, five databases were analyzed in 2014 and then used for searching terms – intervention, review, and asthma. The research reviews on nutrients, family therapy, psychological interventions, alternative medicine, medical procedures, and medication effectiveness were excluded. Based on the gained results, it is critical to notice that public health and asthma control programs must emphasize interventions implementation for which the present review found some effectiveness evidence and to research the interventions that were not appropriately assessed. According to Smeltzer, Bare, Hinkle, and Cheever, asthma symptoms can vary in severity, but most asthmatics experience symptomless periods. Nonetheless, older patients can consider their symptoms as less severe. Asthma symptoms include chest tightness, cough, wheezing, and dyspnea. Asthma can be provoked or caused by cold weather, exercise, respiratory tract infections, and allergens. This disorder is generally diagnosed by familiarizing with the patient’s medical history, conducting peak expiratory flow and auscultating the lungs. In some cases, the doctor can examine pulmonary function through the spirometer test. However, it can be helpful to the older patients. Other possible ways of the diagnosis can be medication therapy trial run, radiological tests and exercise test. At the same time, many guidelines are devoted to asthma disorders; one belongs to the Institute for Clinical System Improvement. According to this guideline, the patient’s diagnosis has to be based on the laboratory test results, pulmonary function tests, physical examination and medical history of the patient. The main asthma triggers are drugs and food, environmental irritants, recreational and occupational allergens or irritants, humidity, temperature, exercise, environmental allergens and viral respiratory infections. This guideline recommends using exhaled nitric oxide, GERD evaluation, CT scans, bronchial provocation testing, chest radiography, allergy testing and accurate spirometry for the diagnosis. Despite many researches and guidelines, asthma still has many gaps that have to be filled. In particular, a great gap exists between evidence-based care and clinical practice in respiratory medicine. In this research, through the Knowledge-to-Action Framework, authors explored the gaps’ nature, barriers, and strategies that can address such disorders as obstructive sleep apnea, chronic obstructive pulmonary disease, and asthma. In the case of the last disorder, it was found that the disease control is provided inadequately, which led to a prevalence of poor asthma control, particularly 50%, while the asthma action plans that only 22% of physicians provide the most critical asthma management component. Therefore, many issues have to be considered and analyzed in the asthma disorder, and a great role in this process plays the decision regarding the treatment approach.

Treatment Approaches

Asthma is generally treated by inhaling corticosteroids that prevent the inflammation of the airways. Additionally, such bronchodilators as inhaled beta-agonists can be used. However, the treatment varies depending on the patient and the disorder’s severity. A great role in asthma treatment plays self-care management. The main point is that patients can make lifestyle choices regarding exercise, nutrition, and bad habits. This includes avoiding asthma-exacerbating factors, protection against cold air, and air humidifier utilization. Hence, self-management programs in health care delivery play a great role in treating asthma. In the case of appropriate implementation, they can influence the disorder and reduce significant financial costs for healthcare systems and personal costs for individuals. The research on this topic aimed to provide an understanding of the current literature on asthma self-management programs among adults and identify the main elements that support or obstruct self-management strategies. In the study, such databases as Web of Science, PubMed, CINAHL, Proquest 5000, and Scopus were used, while the terms for searching were health outcomes, morbidity, self-management, chronic disease, and asthma. As a result, 64 articles were analyzed, and it is critical to notice that despite global recommendations, self-management strategies are poor, and one of the main reasons is that genetic asthma self-management does not engage the person with asthma. In general, the treatment can be divided into pharmacological and non-pharmacological. One the examples of pharmacological treatment can be the short-acting beta-2agonist relievers. They are provided in different forms, including liquid, pill, and inhaled. They are bronchodilators, which “relax the muscles lining the airways that carry air to the lungs within five minutes”. They help to increase the airflow that makes the person breathe easily. The asthma symptoms are relieved in three to six hours, but they have no control over the inflammation. Therefore, this treatment is used to handle intermittent asthma symptoms to prevent asthma symptoms before exercise and provide a “quick relief of symptoms during asthma attacks”. In the case of age groups, this treatment can be less effective for wheezing among children under two years old than older children. Still, bronchodilators are not recommended for children under six months old. However, this is the most common treatment for children aged six and older. The situation with adolescents and adults is similar. Patients with controlled asthma only need to use this treatment up to two days per week. However, the increased usage of the short-acting beta 2 agonists indicates worse asthma control. An example of non-pharmacological treatment can be the bronchial thermoplasty. This effective and safe outpatient procedure provides a long-lasting reduction of severe asthma attacks for adults. The main positive side of this treatment is that it is non-drug and protects patients from the pharmacological treatment’s side effects. BT treatment helps to reduce the airway smooth muscle mass. This is opposite to pharmacological asthma treatments that open up airways by relaxing the muscles in the airway or reducing the swelling. The main positive of this method is that many people with severe asthma reported improvements due to this treatment. Moreover, they experienced not only quality of life improvements but also the severe asthma attacks’ reduction. At the same time, this treatment has limitations because there is always a risk that individual results can differ. The most widespread side effect of this treatment is a temporary worsening of the respiratory-related symptoms that usually appear within one day of the procedure and fade away within seven days. Also, there is an extremely small risk that these symptoms can lead to hospitalization. Therefore, choosing the best treatment approach is difficult because each has its strengths and weaknesses. Nevertheless, bronchial thermoplasty is a more effective treatment. In general, BT is considered a novel therapy for patients. The recent data showed the long-term procedure safety and improvement in asthma exacerbations, quality of life, and reduced health care utilization. Several types of research were conducted regarding the effectiveness of this treatment. The first clinical trial that evaluated BT safety included sixteen patients with mild asthma. They had to use BT with all the related adverse events during the week, which followed the procedure. The results showed a great reduction in airway hyper-responsiveness and an improvement in symptom-free days. The next trial was the first large-scale BT multicenter randomized controlled research. It involved 112 people with severe asthma. Overall, the results showed asthma symptoms and improved quality of life. Therefore, the research has presented similar results because both showed great improvement in asthma symptoms and quality of life. Moreover, this treatment is novel for helping people with asthma and has some great perspectives. Compared with pharmacological, this treatment has more chances and a way to express its effectiveness. Based on the provided research, the results of this treatment are highly positive, and many people report the efficiency of this method. However, the most critical issue is that this treatment does not have side effects like pharmacological treatments, which means it is safer for patients. Hence, it is possible to notice that the non-pharmacological approach is better because it has more perspectives in comparison with the pharmacological treatment.

Conclusion

Overall, asthma is a serious disease that is highly prevalent among children and adults. The main problem is that this prevalence continues to rise, and it is critical to understand this disorder and its treatments. Hence, this paper provided that analysis of different studies and guidelines to identify how to provide asthma diagnosis, from which factors and causes it depends, what role genes play for this disorder and how it should be treated. There are two treatment approaches regarding asthma: pharmacological and non-pharmacological. Based on the analyzed research, it is possible to conclude that the non-pharmacological approach is better because it has more perspectives. In particular, one of the most effective non-pharmacological methods is bronchial thermoplasty, which helps to improve asthma symptoms and quality of life. ? References: 1. Ahmad, N., Ismail, A., & Sulong, S. (2015). Effective public health intervention for asthma: A literature review. Medical Journal of Malaysia, 70. 2. Andrews, K.L., Jones, S.C., Mullan, J. (2014). Asthma self management in adults: A review of current literature. Collegian, 21(1), 33-41.

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