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Aims Vascular peroxidase 1 (VPO1) is a newly identified haem-containing peroxidase that catalyses the oxidation of a variety of substrates by hydrogen peroxide (H2O2). Considering the well-defined effects of H2O2 on the vascular remodelling during hypertension, and that VPO1 can utilize H2O2 generated from co-expressed NADPH oxidases to catalyse peroxidative reactions, the aims of this study were to determine the potential role of VPO1 in vascular remodelling during hypertension. Methods and results The vascular morphology and the expression of VPO1 in arterial tissues of spontaneously hypertensive rats and Wistar–Kyoto rats were assessed. The VPO1 expression was significantly increased concomitantly with definite vascular remodelling assessed by evaluating the media thickness, lumen diameter, media thickness-to-lumen diameter ratio and mean nuclear area in artery media in spontaneously hypertensive rats. In addition, in cultured rat aortic smooth muscle cells we found that the angiotensin II-mediated cell proliferation was inhibited by knockdown of VPO1 using small hairpin RNA. Moreover, the NADPH oxidase inhibitor, apocynin, and the hydrogen peroxide scavenger, catalase, but not the ERK1/2 inhibitor, PD98059, attenuated angiotensin II-mediated up-regulation of VPO1 and generation of hypochlorous acid. Conclusion VPO1 is a novel regulator of vascular smooth muscle cell proliferation via NADPH oxidase–H2O2–VPO1–hypochlorous acid–ERK1/2 pathways, which may contribute to vascular remodelling in hypertension. [ABSTRACT FROM PUBLISHER]

Aims: Collagen, as a component of the extracellular matrix, has been linked to atherosclerotic plaque formation and stability. Activation of LOX-1, a lectin-like oxidized low-density lipoprotein (LDL) receptor-1, exerts a significant role in collagen formation. We examine the hypothesis that LOX-1 deletion may inhibit collagen accumulation in atherosclerotic arteries in LDL receptor (LDLR) knockout (KO) mice. [ABSTRACT FROM PUBLISHER]

Abstract: Objective: Chronic ischemia is associated with alterations in genes that result in myocardial remodeling. An important biochemical basis of cardiac remodeling is generation of reactive oxygen species (ROS). A few studies have suggested that acute ischemia triggers signals for remodeling. We examined the hypothesis that targeted deletion of lectin-like oxidized-LDL receptor (LOX-1) may inhibit signals related to cardiac remodeling. Methods and results: We generated LOX-1 knockout (KO) mice on C57BL/6 (wild-type mice) background, and subjected wild-type and KO mice to ischemia–reperfusion (I–R). The wild-type mice developed a marked reduction in left ventricular systolic pressure and ±dp/dtmax and an increase in left ventricular end-diastolic pressure following I–R, and this change was much less in the LOX-1 KO mice, indicating preservation of left ventricular function with LOX-1 deletion. There was evidence for marked oxidative stress (NADPH oxidase expression, malondialdehyde and 8-isoprostane) following I–R in the wild-type mice, much less so in the LOX-1 KO mice (P <0.01). In concert, collagen deposition (Masson''s trichrome and Picro-sirius red staining) increased dramatically in the wild-type mice, but only half as much in the LOX-1 KO mice (P <0.01). Collagen staining data was corroborated with procollagen-I expression. Further, fibronectin and osteopontin expression increased in the wild-type mice, but to a much smaller extent in the LOX-1 KO mice (P <0.01). Conclusions: These findings provide compelling evidence that LOX-1 is a key modulator of cardiac remodeling which starts immediately following I–R. [Copyright &y& Elsevier]