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Sputum adiponectin effectively identified Western red cedar asthma

Adiponectin in sputum was an effective marker for Western red cedar asthma in patients exposed to cedar dust, according to recent study results.

Researchers conducted methacholine and plicatic acid (PA) challenges on 19 patients with asthmatic symptoms and exposure to cedar dust. FEV₁ was measured, sera was obtained before and after the challenge, and induced sputa was collected 6 hours afterward. Patients who experienced a decline of at least 20% in FEV₁ post-challenge were classified as positive.

Fourteen patients responded positively to either challenge or both, indicating an asthma diagnosis; 12 responded to PA and were diagnosed with Western red cedar asthma (WRCA). ELISA was used to assay sputum supernatants and sera for adiponectin.

After methacholine challenge, the mean sputum adiponectin was 36.4 ± 9 ng/mL. It increased to 119.8 ± 40.6 ng/mL after the plicatic acid challenge (PAC; P<.01).

Researchers conducted subgroup analyses to determine characteristics — including age, BMI, percent predicted baseline FEV₁ and response to challenge — that potentially modified increases in sputum adiponectin.

“PAC-positive subjects had significantly more sputum adiponectin after PAC (166.7 ± 59.9 ng/mL) than after methacholine challenge (41.3 ± 11.9 ng/mL; P<.02),” the researchers wrote.

Among patients with slides available for cell counting, mean sputum eosinophil gains occurred in eight PAC-positive (1.5 ± 0.3% to 14.6 ± 7.6%; P<.05) and five PAC-negative (1.9 ± 0.6% to 5.7 ± 2%; P<.001) participants.

“The concentration of adiponectin in human sputum is responsive to specific inhalational challenge, particularly in those with normal BMI,” the researchers concluded. “Adiponectin in sputum may help us understand the pathophysiology of WRCA, as well as potentially other occupational asthma, and the modifying effect of body mass therein.”

Disclosure: Elkie Fung is employed by the University of British Columbia.