Piper Kadsura Extract Inhibits miR-155 to Protect Lipopolysaccharide-Induced Acute Lung Injury

Abstract

Acute lung injury (ALI) is a common and critical disease encountered in clinical practice. When the disease progresses to a more serious stage, it is called acute respiratory distress syndrome and is associated with a high mortality rate. However, there is a lack of specific drugs for treating this disease; therefore, it is very important to find safe and effective drugs for treatment. Piper kadsura (P. kadsura), part of the of the vin family Piperaceae, has a capability to dispel wind and dampness and its n-butanol extract can provide protection against inflammatory responses, such as inflammatory infiltration and hyperplasia of synovial tissue of joints. In order to explore the therapeutic effect of P. kadsura extract on ALI, we treated HPAEpiC cells with different doses of its extract. We found that after treatment using low-medium and high-dose P. kadsura extract, the optical density value was decreased in HPAEpiC cells as induced by lipopolysaccharide (LPS). In addition, the following were statistically and significantly decreased in a dose-dependent (P < 0.05): the apoptosis rate, cleaved-caspase3 expression, the expression levels of TNF-α, IL-6, and miR-155. However, procaspase 3 increased the expression of miR-155, which can promote LPS-induced apoptosis and the release of inflammatory factors in HPAEpiC cells. The overexpressed miR-155 can weaken the protection conferred by P. kadsura extract on ALI. These results suggest that P. kadsura extract may play a protective role against ALI induced by LPS by decreasing the expression of miR-155.