Systemic mastocytosis (SM) is a risk factor for the development of respiratory symptoms, according to a recently published study in the Journal of Clinical Medicine.
The effects of mast cell activation on the respiratory system
Mast cells contain granules filled with biologically active substances such as heparin and histamine. In response to certain stimuli, mast cells release their granules (a process known as degranulation), leading to an inflammatory response. In addition to their pro-inflammatory role, these granules also contribute to airway constriction and mucus hypersecretion — both of which impair adequate airflow.
What is a mast cell?
Mast cells are specialized cells of the immune system that mediate inflammatory responses and allergic reactions. They are found in the body’s connective tissue.
Long-term mast cell activation can lead to lung tissue remodeling and fibrosis (scar tissue formation), which reduces lung elasticity and its capacity to hold large volumes of air. Mast cell activation has also been shown to contribute to remodeling of the pulmonary blood vessels, leading to pulmonary hypertension and impaired gas exchange between the blood and the lungs.
The effects of SM on the lungs
With this theoretical background, the authors aimed to determine the actual effects of SM on the respiratory system through a retrospective study that included data from over 100 patients with SM and 71 healthy controls.
Spirometry (a pulmonary function test) revealed no significant difference in forced expiratory volume in the first second (FEV1) — a measure of the maximal amount of air exhaled in the first second of a forced expiration — between patients and controls. However, the ratio between FEV1 and vital capacity (VC) — the maximal amount of air that can be inhaled during a forced inspiration — was lower in patients with SM compared to healthy controls. This suggests an airflow obstruction similar to that seen in diseases such as asthma or COPD.
Additionally, the diffusing capacity of the lung for carbon monoxide adjusted for alveolar volume (DLCO/VA) was also reduced in patients with SM, suggesting impaired gas exchange between the lungs and pulmonary blood vessels, likely due to tissue remodeling.
In terms of clinical manifestations, the authors observed that 36% of patients with SM reported difficulty breathing, nearly 10% reported wheezing, and 23% reported chest tightness or pain. Interestingly, there appeared to be no significant difference in the incidence of these symptoms between patients with indolent and advanced forms of mastocytosis.
Read more about SM signs and symptoms
“Mastocytosis appears to be a risk factor for the onset and worsening of respiratory symptoms such as dyspnea, chest tightness, and wheezing,” the authors concluded. “However, the prevalence of these symptoms did not differ significantly across the various clinical subtypes of mastocytosis. Moreover, airway obstruction and impairment of the alveolar–capillary membrane seem to occur independently of the clinical subtype of mastocytosis.”
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