Fibulin-3 may improve vascular health through inhibition of MMP-2/9 and oxidative stress in spontaneously hypertensive rats

Fibulin-3 has been suggested to function in the remodeling of the extracellular matrix, however its role remains unclear in hypertensive vascular remodeling. In the current study, 10 Wistar-Kyoto (WKY) rats (control group) and 30 spontaneously hypertensive rats (SHRs) were used. SHRs were randomized into three groups: The placebo group, intravenous (I.V.) physiological saline; the FBLN-1 group, low-dose fibulin-3 protein (I.V.; 120 ng/kg); and the FBLN-2 group, high-dose fibulin-3 protein (I.V.; 240 ng/kg). Histological analysis was used to analyze vascular remodeling. The expression of fibulin-3, matrix metalloproteinase (MMP)-2, MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-3 were detected by immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction. Oxidative stress was detected by dihydroethidium staining. The systolic blood pressure (SBP) of SHRs was observed to be significantly greater than that of WKY rats (P<0.05). SBP in the FBLN-2 group was significantly reduced compared with the placebo group (182 +/- 12 mmHg vs. 224 +/- 14 mmHg; P<0.05). The thoracic aortic wall thickness in the SHR groups (placebo group, FBLN-1 group and FBLN-2 group) was observed to tbe significantly thicker than in the control group (P<0.01). The wall thickness of the FBLN-2 group was significantly greater than that of the placebo and FBLN-1 groups (124.2 +/- 11.8 mu m vs. 106.9 +/- 9.5 mu m and 96.8 +/- 10.2 mu m; P<0.05). The wall-to-lumen ratios of the placebo, FBLN-1 and FBLN-2 groups were significantly greater than that of the control group (P<0.05). In addition, the expression levels of fibulin-3 and MMP-2/9 at protein and mRNA levels were significantly increased in the thoracic aorta of the placebo group compared with the control group (P<0.05). The levels of MMP-2/9 were significantly reduced in the FBLN-2 group compared with the placebo group (P<0.05). Levels of TIMP-3 however, exhibited no significant differences in the four groups (P>0.05). Reactive oxygen species (ROS) were increased in the placebo group vs. the control group. Fibulin-3 was able to alleviate the levels of ROS in the FBLN groups. It is suggested that fibulin-3 may act as a growth factor in the arteries. In addition, the results indicated that fibulin-3 may reduce the levels of MMP-2 and -9 and oxidative stress in hypertensive vascular remodeling. Upregulating fibulin-3 may be beneficial for improving vascular health and offsetting certain cardiovascular risk factors of hypertension.