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Sputum‐to‐serum hydrogen sulphide ratio as a novel biomarker of predicting future risks of asthma exacerbation
Author(s) -
Suzuki Y.,
Saito J.,
Kikuchi M.,
Uematsu M.,
Fukuhara A.,
Sato S.,
Munakata M.
Publication year - 2018
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1111/cea.13173
Subject(s) - sputum , exacerbation , asthma , medicine , biomarker , immunology , gastroenterology , pathology , chemistry , tuberculosis , biochemistry
Summary Background Increased level of hydrogen sulphide (H 2 S) in sputum is reported to be a new biomarker of neutrophilic airway inflammation in chronic airway disorders. However, the relationship between H 2 S and disease activity remains unclear. Objective We investigated whether H 2 S levels could vary during different conditions in asthma. Method H 2 S levels in sputum and serum were measured using a sulphide‐sensitive electrode in 47 stable asthmatic subjects (S‐ BA ), 21 uncontrolled asthmatic subjects ( UC ‐ BA ), 26 asthmatic subjects with acute exacerbation ( AE ‐ BA ) and 15 healthy subjects. Of these, H 2 S levels during stable, as well as exacerbation states, were obtained in 13 asthmatic subjects. Results Sputum H 2 S levels were significantly higher in the AE ‐ BA subjects compared to the UC ‐ BA and healthy subjects ( P < .05). However, serum H 2 S levels in the AE ‐ BA subjects were lower than in the S‐ BA subjects ( P < .001) and similar to those in healthy subjects. Thus, the sputum‐to‐serum ratio of H 2 S (H 2 S ratio) in the AE ‐ BA subjects was significantly higher than in the S‐ BA , UC ‐ BA and healthy subjects ( P < .05). Among all subjects, sputum H 2 S levels showed a trend to decrease with FEV 1 %predicted and significantly positive correlations with sputum neutrophils (%), sputum IL ‐8 and serum IL ‐8. A multiple linear regression analysis showed that sputum H 2 S was independently associated with increased sputum neutrophils (%) and decreased FEV 1 %predicted ( P < .05). The cut‐off level of H 2 S ratio to indicate an exacerbation was ≥0.34 (area under the curve; 0.88, with a sensitivity of 81.8% and specificity of 72.7%, P < .001). Furthermore, half of the asthmatic subjects with H 2 S ratios higher than the cut‐off level experienced asthma exacerbations over the following 3 months after enrolment. Conclusions The H 2 S ratio may provide useful information on predicting future risks of asthma exacerbation, as well as on obstructive neutrophilic airway inflammation as one of the non‐Th2 biomarkers, in asthma.