Serum adiponectin is positively associated with lung function in young adults, independent of obesity: The CARDIA study

Rationale: Adipose tissue produces adiponectin, an anti-inflammatory protein. Adiponectin deficiency in mice is associated with abnormal post-natal alveolar development. Objective: We hypothesized that lower serum adiponectin concentrations are associated with lower lung function in humans, independent of obesity. We explored mediation of this association by insulin resistance and systemic inflammation. Methods and Measurements: Spirometry testing was conducted at years 10 and 20 follow-up evaluation visits in 2,056 eligible young adult participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Body mass index, serum adiponectin, serum C-reactive protein (a marker of systemic inflammation), and insulin resistance were assessed at year 15. Main Results: After controlling for body mass index, years 10 and 20 forced vital capacity (FVC) were 81 ml and 82 ml lower respectively (p = 0.004 and 0.01 respectively) in the lowest vs. highest adiponectin quartiles. Similarly, years 10 and 20 forced expiratory volume in one second (FEV1) were 50 ml and 38 ml lower (p = 0.01 and 0.09, respectively) in the lowest vs. highest adiponectin quartiles. These associations were no longer significant after adjustment for insulin resistance and C-reactive protein. Serum adiponectin was not associated with FEV1/FVC or peak FEV1. Conclusions: Independent of obesity, lower serum adiponectin concentrations are associated with lower lung function. The attenuation of this association after adjustment for insulin resistance and systemic inflammation suggests that these covariates are on a causal pathway linking adiponectin and lung function.