What are the causes of allergic bronchial asthma?

Bronchitis asthma is a chronic disease. Patients often feel chest tightness, shortness of breath and difficulty breathing, and are often accompanied by incessant coughing. Patients with mild symptoms can relieve the above symptoms on their own, but if they do not seek medical treatment in time, it may cause irreversible airway narrowing. Allergic bronchial asthma is an allergic reaction caused by the body's stimulation by antigens or non-antigen substances.

Individual allergic constitution and external environmental influences are risk factors for the disease. Asthma is related to polygenic inheritance. The prevalence of asthma in relatives of asthma patients is higher than the prevalence in the population, and the closer the relationship, the higher the prevalence; the more serious the patient's condition, the higher the prevalence of his relatives.

1. Allergens

(1) Indoor and outdoor allergens Dust mites are the most common and most harmful indoor allergens and are an important cause of asthma worldwide. Dust mites are found in secretions such as fur, saliva, urine and feces. Fungi are also one of the allergens present in indoor air, especially in dark, humid and poorly ventilated places. Common outdoor allergens: Pollen and grass powder are the most common outdoor allergens that cause asthma attacks. Others include various specific and non-specific inhalants such as animal dander, sulfur dioxide, and ammonia.

(2) Occupational allergens Common allergens include grain powder, flour, wood, feed, tea, coffee beans, silkworms, pigeons, mushrooms, antibiotics (penicillin, cephalosporin), rosin, reactive dyes, persulfate, ethylenediamine, etc.

(3) Drugs and foods Aspirin, propranolol (Inderal) and some non-corticosteroid anti-inflammatory drugs are the main allergens of drug-induced asthma. In addition, foods such as fish, shrimp, crab, eggs, and milk can also trigger asthma.

2. Precipitating factors

Common air pollution, smoking, respiratory infections such as bacteria, viruses, protozoa, parasites, pregnancy, strenuous exercise, climate change; various non-specific stimuli such as inhalation of cold air, distilled water droplets, etc. can induce asthma attacks. In addition, psychological factors can also trigger asthma.

Allergic bronchial asthma:

It is a common disease and also a difficult to cure disease. Modern medicine has confirmed that the cause of the disease is complex, and the pathogenesis is still unclear so far, but it mainly has two factors: allergic reaction and infection.

1. Exogenous (inhalation) asthma

It occurs in children and young people, and the allergens come from outside the body, such as inhalation of dust, pollen, etc., or ingestion of fish, shrimp, etc. Its soluble antigen-specific components are transmitted to specific IgE plasma cells through lymphocytes, producing reagin (i.e. IgE antibodies), which then attach to mast cells and cause sensitization. When allergens invade the human body again, they undergo multiple changes and activate a series of enzyme activities, causing mast cells or alkaliphilic granulocytes to degranulate and release biologically active substances, including histamine (H), eosinophil chemotactic factor (ECF-A), neutrophil chemotactic factor (NCF), slow-reacting allergic substances (SRS-A), platelet aggregation factor (PAF), prostaglandins (PG) and bradypeptides. It acts on the bronchi, causing smooth muscle contraction, mucosal congestion, increased secretion, and extensive airway stenosis, which results in asthma. SRS-A is mainly a chemical medium composed of leukotrienes. It acts to constrict bronchoscopy and increase vascular permeability. It originates from mast cells, neutrophils, etc. Phospholipids in cell membranes produce arachidonic acid (AA) through the action of phospholipase. On the one hand, it undergoes the metabolic pathway of 5-lipoxygenase to produce 5-hydroxyperoxyarachidonic acid (5-HPETE). Under the action of different enzymes, different leukotrienes can be produced. Its action is distal to the bronchi. In asthma patients, the amount of leukotrienes released from lung tissue caused by allergens is closely related to the intensity of bronchial contraction caused by them.

2. Endogenous (infectious) asthma

It is common in adults. The allergens come from the body, mostly caused by respiratory tract infections, products of bacterial or viral infections, stimulation from cold air, and stimulation from physical and chemical factors. The pathological changes include bronchial smooth muscle spasm, mucosal congestion and edema, hypersecretion and increased eosinophils, which cause asthma attacks.