Changes in sputum eicosanoids and inflammatory markers after inhalation challenges with occupational agents

Area of Science:

• Immunology
• Pulmonology
• Occupational Medicine

Background:

• Previous studies linked cysteinyl-leukotrienes (LTs) to atopic asthma after allergen challenge.
• Limited data exist on occupational asthma and inflammatory markers following specific inhalation challenge (SIC) with occupational agents.

Purpose of the Study:

• To investigate differences in lower airway inflammation, cytokines, and eicosanoids between patients with positive and negative SIC responses to occupational agents.
• To compare inflammatory profiles in suspected occupational asthma patients versus healthy controls.

Main Methods:

• Twenty-six patients with suspected occupational asthma and 13 healthy controls underwent spirometry, methacholine challenge, and sputum induction.
• Sputum was analyzed for cytokines and inflammatory mediators, including eicosanoids, at baseline and 24 hours post-SIC.
• SIC was performed using high- or low-molecular-weight occupational agents.

Main Results:

• Eighteen of 26 patients had positive SIC responses (9 early, 2 dual, 7 late asthmatic responses).
• Positive SIC responses correlated with significant increases in sputum eosinophil counts.
• A higher ratio of leukotriene C4 (LTC4) to prostaglandin E2 (PGE2) was observed in patients with positive SIC responses compared to those with negative responses.

Conclusions:

• Patients with positive SIC responses to occupational agents exhibit greater airway eosinophilia.
• Overexpression of LTC4 relative to PGE2 suggests a specific inflammatory pathway in occupational asthma.
• Interleukin-10 levels were decreased in both positive and negative SIC response groups compared to controls.