Atorvastatin suppresses vascular hypersensitivity and remodeling induced by transient adventitial administration of lipopolysaccharide in rats.

Background: The phenotypic transition of vascular smooth muscle cells (VSMCs) from a contractile to a proliferative state markedly affects the pathophysiology of cardiovascular diseases. The adventitial inflammation can promote neointimal formation and vascular remodeling. We used direct administration of lipopolysaccharide (LPS) into the periphery of the carotid artery to investigate the influence of transient adventitial inflammation on vascular remodeling and its potential mechanism.

Methods: Male 15-week-old Wistar rats were randomly assigned to four groups with six rats in each group. The rats of groups I and II were administered distilled water, and group III and IV were treated with fasudil and atorvastatin respectively. All treatments were given daily for 11 days. On day 8, the adventitia in group I was injected with 5 µL sterile saline, and the group II-IV were injected with 5 µL sterilized LPS. The carotid blood flow and femoral blood pressure were measured , and the thickness of vascular intima and middle layer was measured . Serum interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) were determined using enzyme-linked immunosorbent assay (ELISA) assay. And the Rho-associated coiled-coil-containing protein kinase 2 (ROCK2), myosin phosphatase target subunit 1 (MYPT1), myosin light chain (MLC), myocardin, SM-α actin or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected by western blot. The comparisons were made by one-way analysis of variance with Bonferroni's post hoc test. A value of P<0.05 was considered to represent a statistically significant difference.

Results: Transient adventitial inflammation induced by LPS caused no obvious change in basal blood flow, but did lead to vascular hypersensitivity to serotonin. Morphological examinations revealed that the medial layer was the only domain affected, and showed VSMC proliferation and rearrangement. LPS increased serum IL-6 and TNFα contents, ROCK2 expression and activity, and caused changes in the expression levels of some stereotypical VSMC genes. Similar to the Rho-kinase inhibitor fasudil, atorvastatin completely restored the morphological alterations, even increased blood flow.

Conclusions: Our study confirms the beneficial effect of atorvastatin on the vascular system in terms of morphology and function.