Beneficial Effects of Spirulina Supplementation in the Management of Cardiovascular Diseases.

In recent decades, as a result of rising mortality rates due to cardiovascular diseases (CVDs), there has been a growing urgency to find alternative approaches to conventional pharmaceutical treatment to prevent the onset of chronic diseases. Arthrospira platensis, commonly known as Spirulina, is a blue-green cyanobacterium, classified as a "superfood", used worldwide as a nutraceutical food supplement due to its remarkable nutritional value, lack of toxicity, and therapeutic effects. Several scientific studies have evaluated the cardioprotective role of Spirulina. This article presents a comprehensive review of the therapeutic benefits of Spirulina in improving cardio- and cerebrovascular health. It focuses on the latest experimental and clinical findings to evaluate its antihypertensive, antidiabetic, and antihyperlipidemic properties. The objective is to highlight its potential in preventing and managing risk factors associated with cardiovascular disease (CVD).

Role of Dickkopf-3 in Blood Pressure Regulation in Mice and Hypertensive Rats.

BACKGROUND: Dkk3 (Dickkopf-3) is a secreted glycoprotein known for its proapoptotic and angiogenic activity. The role of Dkk3 in cardiovascular homeostasis is largely unknown. Remarkably, the Dkk3 gene maps within a chromosome segment linked to the hypertensive phenotype in spontaneously hypertensive rats (SHR). METHODS: We used Dkk3-/- mice or stroke-resistant (sr) and stroke-prone (sp) SHR to examine the role of Dkk3 in the central and peripheral regulation of blood pressure (BP). We used lentiviral expression vector to rescue Dkk3 in knockout mice or to induce Dkk3 overexpression or silencing in SHR. RESULTS: Genetic deletion of Dkk3 in mice enhanced BP and impaired endothelium-dependent acetylcholine-induced relaxation of resistance arteries. These alterations were rescued by restoring Dkk3 expression either in the periphery or in the central nervous system (CNS). Dkk3 was required for the constitutive expression of VEGF (vascular endothelium growth factor), and the action of Dkk3 on BP and endothelium-dependent vasorelaxation was mediated by VEGF-stimulated phosphatidylinositol-3-kinase pathway, leading to eNOS (endothelial NO synthase) activation both in resistance arteries and the CNS. The regulatory function of Dkk3 on BP was confirmed in SHR stroke-resistant and SHR stroke-prone in which was blunted in both resistance arteries and brainstem. In SHR stroke-resistant, lentiviral expression vector-induced Dkk3 expression in the CNS largely reduced BP, whereas Dkk3 knock-down further enhanced BP. In SHR stroke-prone challenged with a hypersodic diet, lentiviral expression vector-induced Dkk3 expression in the CNS displayed a substantial antihypertensive effect and delayed the occurrence of stroke. CONCLUSIONS: These findings demonstrate that Dkk3 acts as peripheral and central regulator of BP by promoting VEGF expression and activating a VEGF/Akt (protein kinase B)/eNOS hypotensive axis.

A Novel Combination of High-Load Omega-3 Lysine Complex (AvailOm®) and Anthocyanins Exerts Beneficial Cardiovascular Effects.

Omega-3 fatty acids have been shown to exert several beneficial effects in the prevention of cardiovascular and cerebrovascular diseases. The objective of the present study was to analyze the effects of a novel high-load omega-3 lysine complex, AvailOm®, its related constituents and a novel mixture of AvailOm® with specific vasoactive anthocyanins on vascular function in mice resistance artery. Pressure myograph was used to perform vascular reactivity studies. Nitric oxide and oxidative stress were assessed by difluorofluorescein diacetate and dihydroethidium, respectively. Increasing doses of AvailOm® exerted a dose-response vasorelaxation via AMPK-eNOS-mediated signaling. Omega-3 Ethyl Ester was identified as the main bioactive derivative of AvailOm®, being capable of inducing vasorelaxant action to the same extent of entire product. The combination of AvailOm® with a mix of potent vasoactive anthocyanins (C3-glu + DP3-glu + Mal3-glu + Mal3-gal + PEO3-gal), strongly protected mesenteric arteries from vascular dysfunction and oxidative stress evoked by oxidized-LDL. These data demonstrate for the first time the direct effects of AvailOm® on resistance arteries. The evidence that the combination of specific vasoactive anthocyanins and AvailOm® further enhanced the vasculoprotective properties of these compounds, may offer new promising perspectives for preventing the onset of cardiovascular and cerebrovascular events.

Targeting the ASMase/S1P pathway protects from sortilin-evoked vascular damage in hypertension.

Sortilin has been positively correlated with vascular disorders in humans. No study has yet evaluated the possible direct effect of sortilin on vascular function. We used pharmacological and genetic approaches coupled with study of murine and human samples to unravel the mechanisms recruited by sortilin in the vascular system. Sortilin induced endothelial dysfunction of mesenteric arteries through NADPH oxidase 2 (NOX2) isoform activation, dysfunction that was prevented by knockdown of acid sphingomyelinase (ASMase) or sphingosine kinase 1. In vivo, recombinant sortilin administration induced arterial hypertension in WT mice. In contrast, genetic deletion of sphingosine-1-phosphate receptor 3 (S1P3) and gp91phox/NOX2 resulted in preservation of endothelial function and blood pressure homeostasis after 14 days of systemic sortilin administration. Translating these research findings into the clinical setting, we detected elevated sortilin levels in hypertensive patients with endothelial dysfunction. Furthermore, in a population-based cohort of 270 subjects, we showed increased plasma ASMase activity and increased plasma levels of sortilin, S1P, and soluble NOX2-derived peptide (sNOX2-dp) in hypertensive subjects, and the increase was more pronounced in hypertensive subjects with uncontrolled blood pressure. Our studies reveal what we believe is a previously unrecognized role of sortilin in the impairment of vascular function and in blood pressure homeostasis and suggest the potential of sortilin and its mediators as biomarkers for the prediction of vascular dysfunction and high blood pressure.

Analysis of the metabolic switch induced by the spirulina peptide SP6 in high fat diet ApoE-/- mice model: A direct infusion FT-ICR-MS based approach.

Atherosclerosis, dyslipidemia and hypertension are comorbid diseases often found in combination. Among different pharmacological approaches the employment of natural multifunctional peptides is an attractive option as side therapy. Mass spectrometry-based metabolomics provide valuable information on metabolic changes and can be useful to elucidate peptide pharmacodynamics. In this this work we performed a preliminary investigation on the potential effect of a recently characterized Spirulina platensis peptide named SP6 (GIVAGDVTPI) on the modulation of metabolism in a high fat diet ApoE-/- mice atherosclerotic model. A direct infusion Fourier transform ion cyclotron resonance mass spectrometry (DI-FT-ICR-MS) approach was used to elucidate polar and non-polar metabolites extracted by mice plasma following four weeks SP6 treatment. The method delivered fast analysis time, repeatability, high mass accuracy and resolution for unambiguous molecular formula assignment. Multivariate statistical analysis (PLS-DA) highlighted a clear class separation, revealing the alteration of numerous metabolites levels belonging to different classes. In particular sphingolipids, glycerophospholipids, TCA cycle intermediates, and amino acids, which are key players in the atherosclerotic process and progression, were upregulated in saline alone HFD ApoE-/- group, while were sensibly decreased after treatment with SP6 peptide. These results could open the way to further, large-scale, investigation of SP6 peptide effects in the regulation of atherosclerotic disease development and progression, and show the potential of DI-FT-ICR as fast analytical tool to take snaphshots of metabolic changes before moving to targeted MS-based approaches.

PTX3: an inflammatory protein modulating ultrastructure and bioenergetics of human endothelial cells.

BACKGROUND: Pentraxin 3 (PTX3), an acute-phase inflammation protein produced by several cell types, has long been described as a possible biomarker for age-related cardiovascular and cerebrovascular diseases. Although several mechanisms of action have been identified to date in the vascular and immune systems, the direct effects of PTX3 on isolated endothelial cells at morphological and metabolic levels remain unknown. FINDINGS: PTX3 induced cytoplasmic vacuolization and dilution of mitochondrial matrix in isolated, human endothelial cells. Moreover, metabolic assays revealed that PTX3 increases respiratory capacity in support of mitochondrial function, and partially sustains the glycolytic pathway. CONCLUSIONS: PTX3 has, per se, a direct action on ultrastructural and bioenergetic parameters of isolated endothelial cells. This finding can be associated with our previous demonstration of a deleterious effect of PTX3 on the endothelial layer. More studies are needed to clearly demonstrate any direct correlation between these ultrastructural and bioenergetic changes with endothelial dysfunction, especially with regard to age-related cerebro- and cardio-vascular diseases.

Novel Potent Decameric Peptide of Spirulina platensis Reduces Blood Pressure Levels Through a PI3K/AKT/eNOS-Dependent Mechanism.

Considered as a superfood of the future, Spirulina platensis matrix has been extensively used because of its beneficial effect on the management of cardiovascular diseases. However, its nutraceutical properties, bioactive compounds, and molecular mechanisms are unknown. Here, we demonstrate that S platensis matrix processed in vitro by simulated gastrointestinal digestion induces direct endothelial nitric oxide (NO)-mediated vasorelaxation of resistance vessels in mice. To gain insight into the bioactive compounds responsible for this effect, we used a complex multistep peptidomic approach to fractionate the crude digest: of the 5 peptide fractions identified (A-E), only fraction E evoked vasorelaxation. High-resolution mass spectrometry-based screening revealed in E the presence of 4 main peptides (SP3-SP6 [spirulina peptides]), of which only SP6 (GIVAGDVTPI) exerted direct endothelium-dependent vasodilation of ex vivo vessels, an effect occurring via a PI3K (phosphoinositide-3-kinase)/AKT (serine/threonine kinase Akt) pathway converging on NO release. In vivo, administration of SP6 evoked a significant hemodynamic effect, reducing blood pressure, an action absent in eNOS (endothelial NO synthase)-deficient mice. Of note, although lower doses of SP6 had no hemodynamic effects, it still enhanced endothelial NO vasorelaxation. Finally, in an experimental model of arterial hypertension, SP6 exerted an antihypertensive effect, improving endothelial vasorelaxation associated with enhanced serum nitrite levels. Based on our results, this novel decameric peptide may extend the possible fields of application for spirulina-derived peptides and could be developed into a promising nonpharmacological approach for the containment of pathologies associated with vascular NO misregulation.

Akap1 Regulates Vascular Function and Endothelial Cells Behavior.

MitoAKAPs (mitochondrial A kinase anchoring proteins), encoded by the Akap1 gene, regulate multiple cellular processes governing mitochondrial homeostasis and cell viability. Although mitochondrial alterations have been associated to endothelial dysfunction, the role of mitoAKAPs in the vasculature is currently unknown. To test this, postischemic neovascularization, vascular function, and arterial blood pressure were analyzed in Akap1 knockout mice (Akap1-/- ) and their wild-type (wt) littermates. Primary cultures of aortic endothelial cells (ECs) were also obtained from Akap1-/- and wt mice, and ECs migration, proliferation, survival, and capillary-like network formation were analyzed under different experimental conditions. After femoral artery ligation, Akap1-/- mice displayed impaired blood flow and functional recovery, reduced skeletal muscle capillary density, and Akt phosphorylation compared with wt mice. In Akap1-/- ECs, a significant enhancement of hypoxia-induced mitophagy, mitochondrial dysfunction, reactive oxygen species production, and apoptosis were observed. Consistently, capillary-like network formation, migration, proliferation, and AKT phosphorylation were reduced in Akap1-/- ECs. Alterations in Akap1-/- ECs behavior were also confirmed in Akap1-/- mice, which exhibited a selective reduction in acetylcholine-induced vasorelaxation in mesenteric arteries and a mild but significant increase in arterial blood pressure levels compared with wt. Finally, overexpression of a constitutively active Akt mutant restored vascular reactivity and ECs function in Akap1-/- conditions. These results demonstrate the important role of mitoAKAPs in the modulation of multiple ECs functions in vivo and in vitro, suggesting that mitochondria-dependent regulation of ECs might represent a novel therapeutic approach in cardiovascular diseases characterized by endothelial dysfunction.

A cholinergic-sympathetic pathway primes immunity in hypertension and mediates brain-to-spleen communication.

The crucial role of the immune system in hypertension is now widely recognized. We previously reported that hypertensive challenges couple the nervous drive with immune system activation, but the physiological and molecular mechanisms of this connection are unknown. Here, we show that hypertensive challenges activate splenic sympathetic nerve discharge to prime immune response. More specifically, a vagus-splenic nerve drive, mediated by nicotinic cholinergic receptors, links the brain and spleen. The sympathetic discharge induced by hypertensive stimuli was absent in both coeliac vagotomized mice and in mice lacking α7nAChR, a receptor typically expressed by peripheral ganglionic neurons. This cholinergic-sympathetic pathway is necessary for T cell activation and egression on hypertensive challenges. In addition, we show that selectively thermoablating the splenic nerve prevents T cell egression and protects against hypertension. This novel experimental procedure for selective splenic denervation suggests new clinical strategies for resistant hypertension.

The angiogenic factor PlGF mediates a neuroimmune interaction in the spleen to allow the onset of hypertension.

Hypertension is a health problem affecting over 1 billion people worldwide. How the immune system gets activated under hypertensive stimuli to contribute to blood pressure elevation is a fascinating enigma. Here we showed a splenic role for placental growth factor (PlGF), which accounts for the onset of hypertension, through immune system modulation. PlGF repressed the expression of the protein Timp3 (tissue inhibitor of metalloproteinases 3), through the transcriptional Sirt1-p53 axis. Timp3 repression allowed costimulation of T cells and their deployment toward classical organs involved in hypertension. We showed that the spleen is an essential organ for the development of hypertension through a noradrenergic drive mediated by the celiac ganglion efferent. Overall, we demonstrate that PlGF mediates the neuroimmune interaction in the spleen, organizing a unique and nonredundant response that allows the onset of hypertension.