Osthole inhibits intimal hyperplasia by regulating the NF-κB and TGF-β1/Smad2 signalling pathways in the rat carotid artery after balloon injury

Osthole (7-methoxy-8-isopentenoxy-coumarin), a compound extracted from Cnidiummonnieri (L.) Cusson seeds, has been found to exhibit potent therapeutic effects in cancer due to its ability to inhibit inflammation and cell proliferation. However, its effects on arterial wall hypertrophy-related diseases remain unclear. Therefore, in this study, we aimed to investigate the effects of Osthole on intimal hyperplasia in a rat model of carotid artery balloon injury. We established the balloon-induced carotid artery injury rat model in male Sprague-Dawley rats, after which we administered Osthole (20 mg/kg/day or 40 mg/kg/day) or volume-matched normal saline orally by gavage for 14 consecutive days. Intimal hyperplasia and the degree of vascular smooth muscle cell proliferation were then evaluated by histopathological examination of the changes in the carotid artery, as well as by examination of proliferating cell nuclear antigen (PCNA) expression. Tumour necrosis factor-ɑ (TNF-α), interleukin-1β (IL-1β), transforming growth factor-beta (TGF-β1) and PCNA mRNA expression levels were examined by real-time RT-PCR, while nuclear factor-κB (NF-κB (p65)), IκB-α, TGF-β1 and phospho-Smad2 (p-Smad2) protein expression levels were analysed by immunohistochemistry or western blot analysis. We found that Osthole significantly attenuated neointimal thickness and decreased the elevations in PCNA protein expression induced by balloon injury. Moreover, Osthole down-regulated the pro-inflammatory factors TNF-α and IL-1β and NF-κB (p65), whose expression had been upregulated after balloon injury. Moreover, IκB-α protein expression levels increased following Osthole treatment. In addition, the elevations in TGF-β1 and p-Smad2 protein expression induced by balloon injury were both significantly attenuated by Osthole administration. We concluded that Osthole significantly inhibited neointimal hyperplasia in balloon-induced rat carotid artery injury and that the mechanism by which this occurs may involve NF-κB, IL-1β and TNF-ɑ down-regulation, which alleviates the inflammatory response, and TGF-β1/Smad2 signalling pathway inhibition.