Airway and serum adipokines after allergen and diesel exposure in a controlled human crossover study of atopic adults

Adipokines are mediators released from adipose tissue. These proteins are regarded as active elements of systemic and pulmonary inflammation, whose dysregulation can alter an individual's risk of developing allergic lung diseases. Despite this knowledge, adipokine responses to inhaled stimuli are poorly understood. We sought to measure serum and lung adiponectin, leptin, and resistin in an atopic adult study population following exposure to allergen and diesel exhaust (DE). Two types of lung samples including bronchoalveolar lavage (BAL) and bronchial wash (BW), and a time course of serum samples, were collected from the 18 subjects who participated in the randomized, double-blinded controlled human study. The two crossover exposure triads in this study were inhaled DE and filtered air each followed by instilled allergen or saline. Serum and lung adipokine responses to these exposures were quantified using enzyme-linked immunosorbent assay. Allergen significantly increased adiponectin and leptin in BAL, and adiponectin in the BW 48 hours after exposure. Serum leptin and resistin responses were not differentially affected by exposure, but varied over time. Coexposure with DE and allergen revealed significant correlations between the adiponectin/leptin ratio and FEV₁ changes and airway responsiveness measures. Changes in lung and serum adipokines in response to allergen exposure were identified in the context of a controlled exposure study. Coexposure identified a potentially protective role of adiponectin in the lung. This response was not observed in those with baseline airway hyper-responsiveness, or after allergen exposure alone. The clinical relevance of this potentially adaptive adipokine pattern warrants further study.