Simvastatin attenuates pulmonary vascular remodelling by down-regulating matrix metalloproteinase-1 and -9 expression in a carotid artery–jugular vein shunt pulmonary hypertension model in rats

OBJECTIVES: It remains controversial as to whether simvastatin has a beneficial effect on pulmonary artery hypertension. This study aimed to explore the efficacy of simvastatin on haemodynamic changes, pulmonary vascular remodelling and expression of matrix metalloproteinase-1 and -9 (MMP-1,9) in a carotid artery-jugular vein (CA-JV) shunt pulmonary artery hypertension (PAH) model in rats. METHODS: Thirty-six Sprague-Dawley rats were randomized into three groups: Control group, CA-JV group, and Treatment group. A pre-tricuspid systemic-pulmonary shunt from the left common carotid artery to the external jugular vein was established on the CA-JV and Treatment groups, but only ligations of both vessels were performed in Control group. Simvastatin (4 mg/kg/d) was administered to the Treatment group, and placebo to the CA-JV group. Twelve weeks later, the animals underwent a haemodynamic evaluation, followed by pulmonary tissue sampling for morphometry, quantitative real-time PCR and Western blot analysis. RESULTS: By week 12, rats in the CA-JV group had higher right ventricular systolic pressure (RVSP), medial area/total area (MA/TA) and percentage of fibrous tissue (F%) than those in the Control group. These changes were associated with up-regulation of MMP-1,9 mRNA and increased expression of MMP-1,9 proteins. Pretreatment with simvastatin decreased the shunt-induced RVSP, MA/TA and F% in pulmonary arteries. In addition, lung MMP-1,9 mRNA and proteins levels decreased toward normal levels in simvastatin-treated rats. CONCLUSIONS: Simvastatin ameliorated the structural and functional derangements of pulmonary arterioles caused by the CA-JV shunt, partly associated with the suppression of up-regulated MMP-1, as well as MMP-9. Simvastatin may play a role in the treatment of systemic-pulmonary shunt-induced PAH diseases, such as congenital heart disease.