Cupping alleviates lung injury through the adenosine/A_2BAR pathway

Acute lung injury (ALI) is a serious condition. Inflammation plays a crucial role in the pathogenesis of ALI. Cupping, as a part of traditional Chinese medicine, is still a popular complementary and alternative therapy for a variety of ailments including respiratory diseases. However, reliable scientific data about cupping therapy are scarce. Adenosine, a purine nucleoside produced under metabolic stress by the action of extracellular ectonucleotidases (i.e. CD39 and CD73), can attenuate ALI through the A_2BAR receptor. The aim of this study was to investigate the protective effect of cupping in a rat model of ALI and the role of adenosine in it.

Male adult rats were subjected to ALI by intratracheal LPS instillation (0.3 mg/kg). Immediately after intratracheal LPS instillation, vacuum pressure was applied to a sanitized plastic bell cup on the back of the rat by suction for 10 min. Pulmonary injury and inflammation were assessed at 4 h after LPS challenge. The role of adenosine and A_2BAR in cupping's protection after LPS instillation were evaluated.

Cupping alleviated LPS-induced lung injury, reduced inflammation and inhibited NF-kB activation in rats. Cupping upregulated CD39 and CD73 mRNA expression of the skin tissue at the cupping site and increased circulating levels of adenosine. Administration of PSB1115, a specific adenosine A_2BAR receptor antagonist, abolished cupping's beneficial effects in LPS-induced ALI.

Cupping attenuates lung inflammation and injury through the adenosine/A_2BAR pathway. The current study provides evidence-based information about cupping therapy in ALI.