Adipokine adipsin is associated with the degree of lung fibrosis in asbestos-exposed workers

Objectives: Asbestos-exposure causes an inflammatory response driven by alveolar macrophages that can lead to pulmonary fibrosis. In addition to classical inflammatory cytokines, macrophages produce adipokines which regulate the inflammatory response. We studied if adipokines are related to the degree of parenchymal fibrosis, impaired lung function and inflammation in asbestos-exposed subjects.

Methods: Eighty-five males with moderate to heavy occupational exposure to asbestos and unexposed controls were studied. We measured plasma levels of adipokines adiponectin, adipsin, leptin and resistin, IL-6, IL-8, erythrocyte sedimentation rate (ERS), spirometry and D(L,CO). Degree of interstitial lung fibrosis (septal thickening, subpleural lines, parenchymal bands or honeycombing) was scored in classes 0-5 according to a validated scoring system. The subjects were divided into three groups: normal parenchymal finding (fibrosis class 0), borderline changes (classes 0.5-1.5) and fibrosis (i.e. asbestosis; classes 2-5).

Results: Adipsin correlated positively with parenchymal fibrosis (rho=0.412, p<0.001) and there was a linear increasing trend of mean plasma adipsin levels among the three groups of asbestos-exposed subjects (from normal parenchymal finding to borderline changes and to fibrosis) (p<0.0001). Accordingly, plasma adipsin levels correlated positively with the extent of pleural plaques (r=0.245, p=0.043), and negatively with D(L,CO) (r=-0.246, p=0.023). Also, a positive correlation was found between adipsin and inflammatory markers ESR (r=0.315, p=0.008) and IL-6 (r=0.256, p=0.018).

Conclusions: Adipsin was associated with the degree of parenchymal fibrosis, impairment of pulmonary diffusing capacity and with inflammatory activity in asbestos-exposed subjects suggesting that adipsin may have a role in the pathogenesis or as a biomarker in asbestos-induced lung disease.