Regular Dietary Intake of Palmitate Causes Vascular and Valvular Calcification in a Rabbit Model

Aims: Palmitic acid (PA) and oleic acid (OA) are two main dietary fatty acids. Dietary intake of PA has been associated with cardiovascular disease risk, and the effect of OA remains uncertain. Our study aimed to assess the effect of a short-term intake of lard, as source of PA and OA, on aorta and aortic valve.Methods and Results: Rabbits were fed with two lard-enriched diets, containing either elevated levels of PA or of both PA and OA as compared to chow diet. After 16 weeks of each diet, calcification was observed in the aortic intima and in the aortic valve. The extent of calcification did not differ between the two diets. In contrast, rabbits fed chow diet did not develop any calcification. In blood, PA enrichment resulted in decreased lymphocyte and monocyte counts and increased levels of hemoglobin and haematocrit. Levels of the calcification inhibitor fetuin-A were also diminished, whereas creatinine levels were raised. Of note, none of the diets changed cholesterol levels in LDL or HDL. Comprehensive quantitative lipidomics analysis identified diet-related changes in plasma lipids. Dietary PA enrichment led to a drop of polyunsaturated fatty acids (PUFA), in particular of linoleic acid in cholesteryl esters, triglycerides and diacylglycerols (DAG). Ratios of PA to 18-carbon PUFA in DAG were positively correlated with the extent of aortic valve calcification, and inversely with monocyte counts. PA content in blood correlated with aorta calcification.Conclusions: Regular dietary PA intake induces vascular and valvular calcification independently of traditional risk factors. Our findings raise awareness about PA-rich food consumption and its potential deleterious effect on cardiovascular health

Differential Biological Effects of Dietary Lipids and Irradiation on the Aorta, Aortic Valve, and the Mitral Valve

peer reviewedAimsDietary cholesterol and palmitic acid are risk factors for cardiovascular diseases (CVDs) affecting the arteries and the heart valves. The ionizing radiation that is frequently used as an anticancer treatment promotes CVD. The specific pathophysiology of these distinct disease manifestations is poorly understood. We, therefore, studied the biological effects of these dietary lipids and their cardiac irradiation on the arteries and the heart valves in the rabbit models of CVD.Methods and ResultsCholesterol-enriched diet led to the thickening of the aortic wall and the aortic valve leaflets, immune cell infiltration in the aorta, mitral and aortic valves, as well as aortic valve calcification. Numerous cells expressing α-smooth muscle actin were detected in both the mitral and aortic valves. Lard-enriched diet induced massive aorta and aortic valve calcification, with no detectable immune cell infiltration. The addition of cardiac irradiation to the cholesterol diet yielded more calcification and more immune cell infiltrates in the atheroma and the aortic valve than cholesterol alone. RNA sequencing (RNAseq) analyses of aorta and heart valves revealed that a cholesterol-enriched diet mainly triggered inflammation-related biological processes in the aorta, aortic and mitral valves, which was further enhanced by cardiac irradiation. Lard-enriched diet rather affected calcification- and muscle-related processes in the aorta and aortic valve, respectively. Neutrophil count and systemic levels of platelet factor 4 and ent-8-iso-15(S)-PGF2α were identified as early biomarkers of cholesterol-induced tissue alterations, while cardiac irradiation resulted in elevated levels of circulating nucleosomes.ConclusionDietary cholesterol, palmitic acid, and cardiac irradiation combined with a cholesterol-rich diet led to the development of distinct vascular and valvular lesions and changes in the circulating biomarkers. Hence, our study highlights unprecedented specificities related to common risk factors that underlie CVD

Platelets and aortic valve calcification: insights from a rabbit model and from patients with severe aortic stenosis

Background Calcific aortic stenosis (CAS) is the most frequent valvular heart disease in industrialized countries. CAS is characterized by progressive aortic valve remodelling and calcification, which leads to valvular dysfunction and subsequent cardiac impairment. The extent of aortic valve calcification accurately predicts AS severity and prognosis. A recent preclinical study proposed a role for activated platelets in valvular calcification through transforming growth factor-b (TGF-b) or autotaxin-lysophosphatidic acid (LPA). Platelet parameters may therefore represent new circulating biomarkers of CAS progression and outcome. Aim To perform a longitudinal analysis of platelet markers in a new rabbit model of aorta and aortic valve calcification and study their correlation with aortic valve calcium score in patients with severe AS. Methods Twelve-week old male New Zealand White rabbits were fed for 16 weeks (W) with a palm oil-enriched diet (5% palm oil) supplemented with vitamin D2 (25.000U/day/2.5kg) during the first two weeks. Computed tomography (CT) was performed at baseline, W4, W8, W12 and W16 to analyze the appearance of macrocalcifications. Blood samples were collected at the same time points to study the evolution of platelet count. ADP closure time (CT-ADP) was measured in whole blood on a PFA-200. After 16 weeks, the heart and the aorta were collected and fixed for histological analyses of tissue structure (hematoxylin-eosin staining) and calcification (alizarin red staining). In parallel, platelet count, number of activated platelets (CD62P+), CT-ADP, plasma levels of autotaxin, LPA and TGF-b, and CT aortic valve calcium score (CT-AVC) were studied in 36 patients with severe AS undergoing transcatheter aortic valve replacement implantation (TAVI). Results After 16 weeks, all rabbits fed with the palm-oil enriched diet exhibited massive aortic wall calcification, characterized by the presence of large calcification nodules in the aortic media. These aortic macrocalcifications were detectable in vivo by CT in 5 rabbits out of 6. Calcification nodules were also detected in the aortic valve fibrosa of 2 rabbits out of 6 via histological alizarin red staining of explanted hearts. Platelet count decreased as early as after 8 weeks of diet (489 K/μl vs 373K/μl, P<0.05) and kept decreasing progressively along with calcification development. No changes in CT-ADP values were observed over time. In AS patients, as expected, CT-AVC correlated well with peak aortic jet velocity (r=0.49, P=0.0054). Interestingly, CT-AVC was inversely correlated to platelet count (r=-0.52, P=0.0012) and to the number of circulating CD62P+ platelets (r=-0.45, P=0.0073). Although CT-ADP values were above normal values for AS patients, CT-ADP did not correlate with CTAVC. Finally, in agreement with a role for activated platelets as a major source of TGF-b, levels of this cytokine showed good correlation with the number of CD62P+ platelets (r=0.46, P=0.0053). Conclusions Platelet consumption is associated with aortic valve calcification both in our rabbit model and in AS patients. These findings support a role for platelets in this process, possibly via TGF-b. Hence, platelet count might help assessing AS severity and provide prognostic information. This warrants further investigations

Neutrophil extracellular traps infiltrate the lung airway, interstitial, and vascular compartments in severe COVID-19

Infection with SARS-CoV-2 is causing a deadly and pandemic disease called coronavirus disease-19 (COVID-19). While SARS-CoV-2-triggered hyperinflammatory tissue-damaging and immunothrombotic responses are thought to be major causes of respiratory failure and death, how they relate to lung immunopathological changes remains unclear. Neutrophil extracellular traps (NETs) can contribute to inflammation-associated lung damage, thrombosis, and fibrosis. However, whether NETs infiltrate particular compartments in severe COVID-19 lungs remains to be clarified. Here we analyzed postmortem lung specimens from four patients who succumbed to COVID-19 and four patients who died from a COVID-19-unrelated cause. We report the presence of NETs in the lungs of each COVID-19 patient. NETs were found in the airway compartment and neutrophil-rich inflammatory areas of the interstitium, while NET-prone primed neutrophils were present in arteriolar microthrombi. Our results support the hypothesis that NETs may represent drivers of severe pulmonary complications of COVID-19 and suggest that NET-targeting approaches could be considered for the treatment of uncontrolled tissue-damaging and thrombotic responses in COVID-19. © 2020 Radermecker et al. This article is distributed under the terms of an Attribution-Noncommercial-Share Alike-No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution-Noncommercial-Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/)