What is the nature of asthma?

What is the nature of asthma? Bronchial asthma is a chronic airway inflammation involving multiple cells and cellular components. This inflammation is often accompanied by increased airway responsiveness, leading to recurrent wheezing, shortness of breath, chest tightness, or coughing. These symptoms are often accompanied by widespread and variable airflow obstruction during the night and/or morning hours, which may be reversible on its own or with treatment. It is recommended to go to the hospital for examination.

It is currently believed that bronchial asthma is a multi-gene hereditary disease with a clear tendency to familial clustering, and its occurrence is affected by both genetic and environmental factors.

1. Genetic factors

In recent years, with the development of molecular biology technology, progress has been made in the study of asthma-related genes. Chromosomes 5, 6, 11, 12, 13, 14, 17, 19, and 21 may be related to asthma, but the specific relationship is not yet clear. The polygenic inheritance characteristics of asthma are: incomplete penetrance; genetic heterogeneity; polygenic inheritance; synergistic effect. This results in a genetic linkage association being found in one population but not in a different population.

2. Allergens

(1) Allergens Dust mites are the most common allergen and an important cause of asthma worldwide. There are four common types, namely house dust mites, dust mites, dust mites and hairy mites. House dust mites are the most important mites in persistently humid climates. Fungi are also one of the allergens present in indoor air, common ones are Penicillium, Aspergillus, Alternaria, etc. Pollen and grass pollens are the most common outdoor allergens that trigger asthma attacks. Woody plant pollens (tree pollens) often cause spring asthma, while grass pollens (gramineous plants) often cause autumn asthma.

(2) Occupational allergens Common allergens include grain powder, flour, animal fur, wood, silk, linen, kapok, feed, mushrooms, rosin, reactive dyes, ethylenediamine, etc. The mechanism of action of low molecular weight sensitizers is still unclear. High molecular weight sensitizers may sensitize patients and cause asthma attacks through the same allergic reaction mechanism as allergens.

(3) Drugs and food additives: There are two types of drug-induced asthma attacks: specific allergies and non-specific allergies. The former is most commonly caused by allergies to biological products, while the latter occurs in sympathetic blockers and agents that enhance parasympathetic nerve action. Most food allergies are type I allergies. Seafood such as milk, eggs, fish, shrimp and crab, and seasonings can act as allergens and often trigger asthma attacks in patients.

3. Precipitating factors

(1) Infection: The formation and onset of asthma are related to repeated respiratory tract infections, the most common of which are rhinoviruses, followed by influenza viruses, parainfluenza viruses, respiratory syncytial viruses, and coronaviruses.

(2) Climate change: Changes in temperature, humidity, air pressure, and ions in the air can trigger asthma, so it is more common in cold winters or when the climate changes from autumn to winter.

(2) Smoking: Cigarette smoke (including passive smoking) is the main source of indoor triggers and an important asthma trigger, especially for asthmatic children whose parents smoke, who often have asthma attacks due to smoking.

(3) Environmental pollution is closely related to the onset of asthma. Among the harmful irritants that induce asthma, the most common are gas (especially SO2), oil smoke, passive smoking, insecticide sprays, etc. Smoke can irritate the airways of asthma patients who are in a hyper-reactive state, causing bronchi to constrict or even spasm, leading to asthma attacks.

(4) Psychological factors: The patient's nervousness, anxiety, and emotional agitation can also trigger asthma attacks, which are generally believed to be caused by the activation of the cerebral cortex and vagus nerve or hyperventilation.

(5) Exercise: Asthma patients may experience an asthma attack after strenuous exercise, which is often manifested by cough, chest tightness, wheezing, and wheezing can be heard by auscultation. Most patients will be relieved within an hour. Although some patients do not have asthma symptoms, exercise may induce bronchial smooth muscle spasm.