Why are asthma patients susceptible to frequent infections?

From the Guidelines

Asthma patients are susceptible to frequent infections primarily because of their compromised respiratory defenses and the effects of asthma medications, which can be attributed to the chronic inflammation in their airways damaging the protective epithelial lining and reducing the effectiveness of the mucociliary clearance mechanism 1. This compromised state is further exacerbated by the use of inhaled corticosteroids, which, while essential for controlling asthma symptoms, can suppress local immune responses in the airways when used at higher doses. The structural changes in asthmatic airways, including mucus hypersecretion and bronchial remodeling, create favorable environments for microbial growth, as noted in the expert panel report 3 (EPR-3) guidelines for the diagnosis and management of asthma 1.

Some key factors contributing to the susceptibility of asthma patients to frequent infections include:

• Chronic inflammation in the airways
• Damage to the protective epithelial lining
• Reduced effectiveness of the mucociliary clearance mechanism
• Suppression of local immune responses by inhaled corticosteroids
• Structural changes in the airways, such as mucus hypersecretion and bronchial remodeling

Asthma exacerbations often trigger a cycle where infections worsen asthma symptoms, leading to increased medication use, which may further suppress immunity. To reduce infection risk, patients should:

• Maintain optimal asthma control with appropriate medication use
• Practice good hand hygiene
• Consider annual influenza vaccination and pneumococcal vaccination as recommended
• Rinse their mouth after using inhaled steroids to prevent oral thrush
• Promptly treat respiratory infections to prevent asthma flare-ups, as suggested by studies on the use of antibiotics to treat asthma exacerbations 1 and the proceedings of the ATS workshop on refractory asthma 1.

Overall, the management of asthma and prevention of frequent infections requires a comprehensive approach that addresses the underlying pathophysiology of the disease, the effects of medications, and the importance of preventive measures.

From the Research

Asthma and Infection Susceptibility

Asthma patients are susceptible to frequent infections due to several factors, including:

• Chronic inflammation of the airways, which can lead to increased mucus production and impaired mucociliary clearance, making it easier for pathogens to colonize and infect the airways 2
• Airway hyperresponsiveness, which can cause excessive inflammation and damage to the airway epithelium, making it more susceptible to infection 3, 4
• Immunodeficiency, which can be associated with asthma, making patients more prone to infections 2
• Environmental factors, such as exposure to allergens, tobacco smoke, and air pollution, which can trigger allergic reactions and irritate the airways, increasing the risk of infection 2, 5

Pathophysiology of Asthma

The pathophysiology of asthma involves:

• Inflammation of the airways, which is characterized by the presence of increased numbers of eosinophils, neutrophils, lymphocytes, and plasma cells in the bronchial tissues, bronchial secretions, and mucus 3
• Airway hyperresponsiveness, which is documented by decreased bronchial airflow after bronchoprovocation with methacholine or histamine 3, 4
• Remodeling of the airways, which can produce long-term structural changes, such as smooth muscle hypertrophy, lamina reticularis thickening, and mucus gland hypersecretion 3, 2

Relationship between Asthma and Infection

There is evidence to suggest that asthma is associated with an increased susceptibility to infection, and that infections can trigger and promote disease progression in asthmatic patients 2, 6

• The role of infections as triggers and promoters of disease progression is well established, but the impact of asthma as a predisposing condition to infection has not been fully addressed 2
• Further research is needed to understand the relationship between asthma and infection, and to develop effective strategies for preventing and treating infections in asthmatic patients 2, 5