Food Derived Peptides Reduced COX-2 Expression in Angiotensin II-Stimulated Adventitial Fibroblasts

Prostanoids modulate the pathogenesis of vascular diseases such as atherosclerosis, in which inflammation has an important role. It is well known that inducible Ciclooxygenase-2 (COX-2) is responsible for prostanoid production associated with inflammation. Angiotensin II may be implicated through the expression of COX-2 in the vascular wall. The purpose of this study was to examine in angiotensin II-stimulated adventitial fibroblasts the anti-inflammatory activity of different food peptides by inhibiting COX-2 expression, and the production of pro-inflammatory prostanoids. Fibroblasts from aorta of Sprague-Dawley rats were incubated with different food derived peptides followed by incubation with Angiotensin II. COX-2 expression was determined by western blot, transcriptional activity by luciferase assays and prostaglandin E2 by enzyme immunoassay. COX-2 expression was inhibited in the presence of Val-Pro-Pro (bovine β-casein 84–86), Arg-Asp-Ile-Leu-Asn-Gln (ovalbumin 84–89) and Tyr-Arg-Gly-Gly-Leu-Glu-Pro-Ile-Asn-Phe (ovalbumin 125–134). Angiotensin II-induced prostaglandin E2 production was also reduced by all the above-mentioned sequences. The incubation with ovalbumin-derived peptides displayed a significant reduction of COX-2 promoter activity compared to the stimuli with Angiotensin II in transiently transfected cells. These three sequences could potentially be used as functional food ingredients to reduce inflammation related to cardiovascular diseases.

G protein-coupled estrogen receptor inhibits vascular prostanoid production and activity

Complications of atherosclerotic vascular disease, such as myocardial infarction and stroke, are the most common causes of death in postmenopausal women. Endogenous estrogens inhibit vascular inflammation-driven atherogenesis, a process that involves cyclooxygenase (COX)-derived vasoconstrictor prostanoids such as thromboxane A2. Here, we studied whether the G protein-coupled estrogen receptor (GPER) mediates estrogen-dependent inhibitory effects on prostanoid production and activity under pro-inflammatory conditions. Effects of estrogen on production of thromboxane A2were determined in human endothelial cells stimulated by the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-α). Moreover,Gper-deficient (Gper−/−) and WT mice were fed a pro-inflammatory diet and underwent ovariectomy or sham surgery to unmask the role of endogenous estrogens. Thereafter, contractions to acetylcholine-stimulated endothelial vasoconstrictor prostanoids and the thromboxane-prostanoid receptor agonist U46619 were recorded in isolated carotid arteries. In endothelial cells, TNF-α-stimulated thromboxane A2production was inhibited by estrogen, an effect blocked by the GPER-selective antagonist G36. In ovary-intact mice, deletion ofGperincreased prostanoid-dependent contractions by twofold. Ovariectomy also augmented prostanoid-dependent contractions by twofold in WT mice but had no additional effect inGper−/−mice. These contractions were blocked by the COX inhibitor meclofenamate and unaffected by the nitric oxide synthase inhibitorl-NG-nitroarginine methyl ester. Vasoconstrictor responses to U46619 did not differ between groups, indicating intact signaling downstream of thromboxane-prostanoid receptor activation. In summary, under pro-inflammatory conditions, estrogen inhibits vasoconstrictor prostanoid production in endothelial cells and activity in intact arteries through GPER. Selective activation of GPER may therefore be considered as a novel strategy to treat increased prostanoid-dependent vasomotor tone or vascular disease in postmenopausal women.