Asthma is a chronic airway inflammatory disease clinically characterized by recurrent episodes of wheezing, breathlessness, cough, and chest tightness, varying in severity and frequency, and often accompanied by airflow obstruction. Associated, usually, spontaneously or reversible with treatment, under the influence of hypersensitivity, inflammation and structural changes in the respiratory system. Asthma-associated inflammation involves mast cells, eosinophils, T lymphocytes, neutrophils, and epithelial cells, which trigger mediators such as histamine and leukotrienes and prostaglandins that contribute to the pathological state of the body, causing narrowing of the airways, secretion of mucus, Symptoms of overproduction and tightening of smooth muscles appear.
The most well-known causes of asthma, genetics and external factors, are involved in a network of interactions of multifactorial origin. They include variations in genes matching the immune system and airway structure for genetic contributions; Whereas for environmental factors: allergen exposure, respiratory infections, tobacco smoke, pollutants, or occupational irritants. Generally, the disease presents from childhood, but it can present at any age with different phenotypes. Influencing environmental factors include genetic susceptibility and these vary markedly phenotypically, for example, some people have allergic asthma with a history of atopy and allergies such as hay fever and eczema; Others have non-allergic asthma that may have symptoms that include exercise, stress, or cold air.
The inflammation underlying asthma has immune mechanisms that involve both innate and adaptive immunity. In allergic asthma, the immunological response is dominated by T-helper type 2 (Th2) cells that release cytokines such as interleukin (IL)-4, IL-5, and IL-13. These cytokines promote the production of immunoglobulin E (IgE) antibodies, recruit eosinophils, and initiate increased mucus secretion, leading to airway inflammation and hyperresponsiveness. Other inflammatory pathways may occur in non-allergic asthma, including neutrophilic inflammation, with which common anti-asthma drugs such as steroids have limited therapeutic effect. Both types of asthma can lead to structural changes over time in airway remodeling that may result in airway wall thickening, increased smooth muscle mass, and formation of fibrotic tissue that are responsible for contributing to fixed airflow limitation in some patients. It is possible
Asthma is classified into four categories according to severity: intermittent, mild persistent, moderate persistent, and severe persistent. This classification is based on the frequency and intensity of symptoms as well as decreased lung function. The aim of asthma control is to control symptoms, prevent exacerbations, reduce the need for rescue medications, and reduce the chance of long-term complications. A combination of medicinal and non-pharmacological strategies are used to achieve this objective. Pharmacological treatments include the use of controller medications such as inhaled corticosteroids (ICS) plus long-acting beta-agonists (LABAs) plus leukotriene receptor antagonists (LTRAs) plus biologic therapy, complemented by reliever medications such as short-acting beta agonists (SABAs). Target specific inflammatory pathways. Non-pharmacological approaches deal with patient education as well as allergen avoidance, smoking cessation, weight management, and pulmonary rehabilitation.
Yet now, despite profound advances in the understanding of the disease, asthma is still a major health problem worldwide, accounting for a large proportion of morbidity, mortality, and economic burden. There are wide variations in the prevalence of asthma between populations depending on genetic but especially environmental and socio-economic factors. In many cases, asthma is underdiagnosed and undertreated, resulting in preventable exacerbations, reduced quality of life, and reduced productivity. An asthma exacerbation, also known as an asthma attack, involves worsening symptoms and an acute or sub-acute increase in lung function, which may require immediate medical care. All of these growths can be ignited by a number of triggers, including viral infections, exposure to allergens, air pollution or non-adherence to treatment regimens. Some severe overgrowths can actually lead to respiratory failure and sometimes death, therefore underscoring the need for early detection and appropriate management.
Pathophysiology Asthma is a complex puzzle, involving many different processes that may interact, such as inflammation, airway hyperresponsiveness, and structural changes. Airway hypersensitivity refers to an exaggerated bronchoconstrictor response to all types of stimuli, whether they are allergens, exercise, or irritants. The high sensitivity is possible considering that core features of asthma show evidence of inflammatory activation and structural abnormalities in the airways. Eosinophilic is the most common form of inflammation in asthma, nevertheless, other patterns of inflammatory response, predominantly neutrophilic or mixed inflammation, are common in those with more severe forms of the disease or those not subject to treatment resistance. Structural changes, also known as airway remodeling, include phenomena such as subepithelial fibrosis, goblet cell hyperplasia, smooth muscle hypertrophy, and angiogenesis, all of which lead to the chronicity and potentially progressive nature of asthma.
It is important to note that asthma does not manifest as one disease, but rather is a collection of different phenotypes and endotypes often called syndromes, each of which has distinct clinical as well as biological features. Positive symptoms are considered phenotypes based on observable characteristics such as age of onset, trigger, or severity while endotypes define the underlying pathophysiology mechanisms of the disease. For example, eosinophilic asthma is an endotype characterized by high eosinophil numbers and a Th2-dominant immune response, whereas neutrophilic asthma is characterized by neutrophilic inflammation, which may be caused by Th17 pathways. Thus, by recognizing different asthma subtypes, personalized treatments such as biologics targeting specific cytokines or receptors involved in the inflammatory process were developed.
The natural history of asthma varies from person to person, such as when it disappears on its own in children or adolescents, and in other cases becomes chronic and persistent. Factors influencing the course of asthma include age of onset, severity of initial symptoms, degree of airway inflammation, comorbidities, and adherence to treatment. To a lesser extent, there may be a more severe type of asthma, characterized by frequent exacerbations, fixed airflow obstruction, and poor response to all standard treatment options. Intervention at an early stage is important to prevent these long-term complications and optimize outcomes in this subtype.
