The polysaccharide from purple sweet potato ( Ipomoea batatas (L.) Lam) alleviates lipopolysaccharide-induced acute lung injury in mice via the VIP/ cAMP/PKA/AQPs signaling pathway

Background: The polysaccharide (PSP) from purple sweet potato has great potential for regulating apoptosis, but its regulatory role in acute lung injury (ALI) is unknown. Methods: The objective of this study was to investigate the protective effect of PSP on lipopolysaccharide (LPS)induced ALI in mice and lung epithelial A549 cells and its mechanism. Moreover, subacute toxicity evaluation of PSP was carried out on ICR mice. Results: The results showed that compared with the ALI group, PSP significantly reduced the total protein content, wet-to-dry (W/D) ratio, the number of neutrophils, lymphocytes, and monocytes. Moreover, PSP was able to reduce cell apoptosis, the levels of macrophage inflammatory protein-2 (MIP-2), intercellular adhesion molecule- 1 (ICAM-1), tumor necrosis factor-alpha (TNF-alpha), malondialdehyde (MDA) and myeloperoxidase (MPO) and increase the level of superoxide (SOD). In addition, PSP could up-regulate the levels of VIP, cAMP, p-PKA/PKA and AQP1 in mice and A549 cells. And PSP exhibited no apparent adverse effects on the mice. Conclusions: PSP had a protective effect on LPS-induced ALI in mice and lung epithelial A549 cells, which may be related to the inflammatory response and via VIP/cAMP/PKA/AQPs signaling pathway. Thus, PSP may be a promising pharmacologic agent for ALI therapy.