Asthma - Signs and Symptoms

Asthma, derived from the Greek word for panting, is a chronic inflammatory condition affecting the Airways. It causes the narrowing of air passages, making it difficult to breathe. People with asthma may experience exacerbations or asthma attacks triggered by various environmental factors. These attacks can lead to inflammation in the lungs, further constricting the Airways and potentially posing a life-threatening situation. To understand asthma better, it's important to explore the underlying mechanisms and manifestations of this condition.

Understanding Asthma

Asthma is characterized by chronic inflammation in the Airways, which affects the respiratory system. The lungs consist of the trachea, which branches into the right and left bronchi, further dividing into thousands of bronchioles. Within the bronchioles, there is the lumen, mucosa, and submucosa. The mucosa includes the inner lining of epithelial cells, the lamina propria, and the submucosa housing smooth muscle.

Inflammatory Process in Asthma

In asthma, eosinophils, a type of white blood cell, are often found beneath the epithelium in the lamina propria. These eosinophils contain granules filled with soluble chemical mediators like histamines, leukotrienes, prostaglandins, and platelet-activating factors. When triggered by environmental factors such as cigarette smoke, eosinophils release their granules, resulting in the spillage of these chemical mediators. This leads to a strong inflammatory reaction in the bronchial walls, causing two significant changes. First, the smooth muscles surrounding the bronchioles start to spasm, narrowing the airway. Second, there is an increased secretion of mucus into the already narrow Airways, further exacerbating the breathing difficulties. Consequently, asthma is classified as a type of obstructive pulmonary disease. Initially, these inflammatory changes are reversible, but over time, irreversible changes such as edema, scarring, and fibrosis occur. These changes lead to the thickening of the epithelial basement membrane, permanently reducing the diameter of the airways.

Immune Cell Involvement

Th2 cells, a subtype of immune cells, play a crucial role in asthma, as well as atopic dermatitis and allergic rhinitis, forming what is known as the atopic triad. Th2 cells release cytokines to communicate with other cells. Interleukin 5, a specific cytokine, attracts and activates eosinophils. Blocking interleukin 5 has shown some efficacy in helping asthma patients. However, some asthma patients have low levels of Th2 cells but high levels of neutrophils, another class of immune cells. Neutrophils are highly inflammatory phagocytic cells that engulf infected or dead cells. The exact role of neutrophils in promoting asthma is not yet fully understood. Interleukin 8, released by neutrophils, appears to play a significant role in the disease. Patients with neutrophilic asthma often experience a more severe form of asthma compared to those with eosinophilic asthma.

Genetic and Environmental Factors

While the exact causes of asthma remain unknown, it is believed to be influenced by a combination of genetic and environmental factors. Certain genes have been identified as increasing the risk of developing asthma. Additionally, having a family history of asthma increases an individual's susceptibility to the condition. Environmental factors also play a significant role, with the hygiene hypothesis suggesting that reduced early immune system exposure to bacteria and viruses may increase the risk of developing asthma. The overall proportion of immune cell subtypes may be altered due to this reduced exposure. Childhood asthma, typically diagnosed before the age of 12, is believed to have a stronger genetic influence, while asthma onset in adulthood is more likely to be triggered by environmental factors.

Common Triggers of Asthma

The substances that trigger asthma attacks can vary from person to person. Some common triggers include air pollution, such as cigarette smoke and car exhaust, as well as allergens like dust, pet dander, cockroaches, and mold. Certain medications, including aspirin and beta blockers, have also been known to trigger symptoms in individuals with asthma.

Symptoms of Asthma

The symptoms of asthma include persistent coughing, a feeling of chest tightness, dyspnea or difficulty breathing, and wheezing, which produces a high-pitched whistling sound, especially during exhalation. In some cases, individuals with bronchial asthma may expel Kerch Minh spirals, which are spiral-shaped mucus plugs from the small bronchi. These mucus plugs are particularly hazardous as they block the exchange of air and hinder the delivery of inhaled medications to the site of inflammation. The mucus may also contain Charcot Laden crystals, needle-shaped crystals formed by the breakdown of eosinophils.

Classification of Asthma Severity

Asthma severity can be classified based on the frequency of symptoms, including nighttime and early morning symptoms, as well as measurements such as FEV1 (forced expiratory volume in one second) and PEFR (peak expiratory flow rates). The types of asthma range from intermittent asthma, mild persistent asthma, and moderate persistent asthma to severe persistent asthma, with each category indicating an increasing level of severity and frequency of symptoms.

Management and Treatment

While there is no cure for asthma, various treatments are available to manage the symptoms and prevent asthma attacks. Individuals with asthma should try to avoid or minimize contact with triggering substances. This can be achieved through measures such as vacuuming, removing carpets and rugs, and making environmental changes, such as reducing moisture levels in the case of mold growth. Medications play a vital role in asthma management, with bronchodilators like short-acting beta-2 agonists and anticholinergic medications often administered through emergency inhalers to provide immediate relief by relaxing the smooth muscles in the lungs. Severe asthma may require additional treatments such as daily corticosteroids, long-acting beta-agonists, or leukotriene antagonists. In rare cases, intravenous corticosteroids, magnesium sulfate, or oxygen therapy may be necessary.

Conclusion

Asthma is a chronic inflammatory condition characterized by narrowing Airways, leading to difficulty in breathing. The inflammatory process involves eosinophils, chemical mediators, and immune cell subtypes. Genetic and environmental factors contribute to the development of asthma, and triggers can vary among individuals. Recognizing the signs and symptoms of asthma is essential for proper diagnosis and classification of severity. While there is no cure, effective management strategies and medications are available to help control symptoms and reduce the frequency of asthma attacks, improving the quality of life for individuals with asthma.