Mechanisms of fibrous cap formation in atherosclerosis.

The fibrous cap is formed by smooth muscle cells that accumulate beneath the plaque endothelium. Cap rupture is the main cause of coronary thrombosis, leading to infarction and sudden cardiac death. Therefore, the qualities of the cap are primary determinants of the clinical outcome of coronary and carotid atherosclerosis. In this mini-review, we discuss current knowledge about the formation of the fibrous cap, including cell recruitment, clonal expansion, and central molecular signaling pathways. We also examine the differences between mouse and human fibrous caps and explore the impact of anti-atherosclerotic therapies on the state of the fibrous cap. We propose that the cap should be understood as a neo-media to substitute for the original media that becomes separated from the surface endothelium during atherogenesis and that embryonic pathways involved in the development of the arteria media contribute to cap formation.LA-H is supported by a grant from the Danish Cardiovascular Academy (PD2Y-2022003-DCA), JA-J by a grant from the Aarhus University Research Foundation (Starting Grant, AUFF-E-201 9-7- 23) and JB by grants from the Novo Nordisk Foundation (NNF17OC0030688), Ministerio de Ciencia e Innovación with cofunding from the European Regional Development Fund (PID2019-108568RB-I00), and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 866240). The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MICIN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (grant CEX2020- 001041-S funded by MICIN/AEI/10.13039/501100011033).S

High-fructose feeding does not induce steatosis or non-alcoholic fatty liver disease in pigs

Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent condition that has been linked to high-fructose corn syrup consumption with induction of hepatic de novo lipogenesis (DNL) as the suggested central mechanism. Feeding diets very high in fructose (> 60%) rapidly induce several features of NAFLD in rodents, but similar diets have not yet been applied in larger animals, such as pigs. With the aim to develop a large animal NAFLD model, we analysed the effects of feeding a high-fructose (HF, 60% w/w) diet for four weeks to castrated male Danish Landrace-York-Duroc pigs. HF feeding upregulated expression of hepatic DNL proteins, but levels were low compared with adipose tissue. No steatosis or hepatocellular ballooning was seen on histopathological examination, and plasma levels of transaminases were similar between groups. Inflammatory infiltrates and the amount of connective tissue was slightly elevated in liver sections from fructose-fed pigs, which was corroborated by up-regulation of macrophage marker expression in liver homogenates. Supported by RNA-profiling, quantitative protein analysis, histopathological examination, and biochemistry, our data suggest that pigs, contrary to rodents and humans, are protected against fructose-induced steatosis by relying on adipose tissue rather than liver for DNL.The study was supported by a Synergy Grant from the Novo Nordisk Foundation (NNF14OC0011537) and by the Danish National Resarch Foundation (ATLAS center). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Mechanisms of fibrous cap formation in atherosclerosis

The fibrous cap is formed by smooth muscle cells that accumulate beneath the plaque endothelium. Cap rupture is the main cause of coronary thrombosis, leading to infarction and sudden cardiac death. Therefore, the qualities of the cap are primary determinants of the clinical outcome of coronary and carotid atherosclerosis. In this mini-review, we discuss current knowledge about the formation of the fibrous cap, including cell recruitment, clonal expansion, and central molecular signaling pathways. We also examine the differences between mouse and human fibrous caps and explore the impact of anti-atherosclerotic therapies on the state of the fibrous cap. We propose that the cap should be understood as a neo-media to substitute for the original media that becomes separated from the surface endothelium during atherogenesis and that embryonic pathways involved in the development of the arteria media contribute to cap formation

Fibrous Caps in Atherosclerosis Form by Notch-Dependent Mechanisms Common to Arterial Media Development.

Atheromatous fibrous caps are produced by smooth muscle cells (SMCs) that are recruited to the subendothelial space. We tested whether the recruitment mechanisms are the same as in embryonic artery development, which relies prominently on Notch signaling to form the subendothelial medial SMC layers. Notch elements were expressed in regions of fibrous cap in human and mouse plaques. To assess the causal role of Notch signaling in cap formation, we studied atherosclerosis in mice where the Notch pathway was inactivated in SMCs by conditional knockout of the essential effector transcription factor RBPJ (recombination signal-binding protein for immunoglobulin kappa J region). The recruitment of cap SMCs was significantly reduced without major effects on plaque size. Lineage tracing revealed the accumulation of SMC-derived plaque cells in the cap region was unaltered but that Notch-defective cells failed to re-acquire the SMC phenotype in the cap. Conversely, to analyze whether the loss of Notch signaling is required for SMC-derived cells to accumulate in atherogenesis, we studied atherosclerosis in mice with constitutive activation of Notch signaling in SMCs achieved by conditional expression of the Notch intracellular domain. Forced Notch signaling inhibited the ability of medial SMCs to contribute to plaque cells, including both cap SMCs and osteochondrogenic cells, and significantly reduced atherosclerosis development. Sequential loss and gain of Notch signaling is needed to build the cap SMC population. The shared mechanisms with embryonic arterial media assembly suggest that the cap forms as a neo-media that restores the connection between endothelium and subendothelial SMCs, transiently disrupted in early atherogenesis.This study was supported by a grant from the Ministerio de Ciencia e Innovación with cofunding from the European Regional Development Fund (SAF2016- 75580-R and PID2019-108568RB-I00 to J.F. Bentzon and SAF2016-78370-R to J.L. de la Pompa) and from the Novo Nordisk Foundation (NNF17OC0030688 to. J.F. Bentzon). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Cholesterol lowering depletes atherosclerotic lesions of smooth muscle cell-derived fibromyocytes and chondromyocytes

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EDUCACIÓN AMBIENTAL Y SOCIEDAD. SABERES LOCALES PARA EL DESARROLLO Y LA SUSTENTABILIDAD

Este texto contribuye al análisis científico de varias áreas del conocimiento como la filosofía social, la patología, la educación para el cuidado del medio ambiente y la sustentabilidad que inciden en diversas unidades de aprendizaje de la Licenciatura en Educación para la Salud y de la Maestría en Sociología de la SaludLas comunidades indígenas de la sierra norte de Oaxaca México, habitan un territorio extenso de biodiversidad. Sin que sea una área protegida y sustentable, la propia naturaleza de la región ofrece a sus visitantes la riqueza de la vegetación caracterizada por sus especies endémicas que componen un paisaje de suma belleza

Lineage tracing of cells involved in atherosclerosis

Background and aims: Despite the clinical importance of atherosclerosis, the origin of cells within atherosclerotic plaques is not fully understood. Due to the lack of a definitive lineage-tracing strategy, previous studies have provided controversial results about the origin of cells expressing smooth muscle and macrophage markers in atherosclerosis. We here aim to identify the origin of vascular smooth muscle (SM) cells and macrophages within atherosclerosis lesions. Methods: We combined a genetic fate mapping approach with single cell expression analysis in a murine model of atherosclerosis. Results: We found that 16% of CD68-positive plaque macrophage-like cells were derived from mature SM cells and not from myeloid sources, whereas 31% of αSMA-positive smooth muscle-like cells in plaques were not SM-derived. Further analysis at the single cell level showed that SM-derived CD68+ cells expressed higher levels of inflammatory markers such as cyclooxygenase 2 (Ptgs2, p = 0.02), and vascular cell adhesion molecule (Vcam1, p = 0.05), as well as increased mRNA levels of genes related to matrix synthesis such as Col1a2 (p = 0.01) and Fn1 (p = 0.04), than non SM-derived CD68+ cells. Conclusions: These results demonstrate that smooth muscle cells within atherosclerotic lesions can switch to a macrophage-like phenotype characterized by higher expression of inflammatory and synthetic markers genes that may further contribute to plaque progression

Genetic dissection of the Vav2-Rac1 signaling axis in vascular smooth muscle cells

Vascular smooth muscle cells (vSMCs) are key in the regulation of blood pressure and the engagement of vascular pathologies, such as hypertension, arterial remodeling, and neointima formation. The role of the Rac1 GTPase in these cells remains poorly characterized. To clarify this issue, we have utilized genetically engineered mice to manipulate the signaling output of Rac1 in these cells at will using inducible, Cre-loxP-mediated DNA recombination techniques. Here, we show that the expression of an active version of the Rac1 activator Vav2 exclusively in vSMCs leads to hypotension as well as the elimination of the hypertension induced by the systemic loss of wild-type Vav2. Conversely, the specific depletion of Rac1 in vSMCs causes defective nitric oxide vasodilation responses and hypertension. Rac1, but not Vav2, also is important for neointima formation but not for hypertension-driven vascular remodeling. These animals also have allowed us to dismiss etiological connections between hypertension and metabolic disease and, most importantly, identify pathophysiological programs that cooperate in the development and consolidation of hypertensive states caused by local vascular tone dysfunctions. Finally, our results suggest that the therapeutic inhibition of Rac1 will be associated with extensive cardiovascular system-related side effects and identify pharmacological avenues to circumvent them.Fil: Fabbiano, Salvatore. Universidad de Salamanca; EspañaFil: Menacho Márquez, Mauricio Ariel. Universidad de Salamanca; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Sevilla, María A.. Universidad de Salamanca; EspañaFil: Albarrán Juárez, Julián. Max-planck-instituts Für Herz- Und Lungenforschung; AlemaniaFil: Zheng, Yi. Cincinnati Children's Hospital Research Foundation; Estados UnidosFil: Offermanns, Stefan. Max-planck-instituts Für Herz- Und Lungenforschung; AlemaniaFil: Montero, María J.. Universidad de Salamanca; EspañaFil: Bustelo, Xosé R.. Universidad de Salamanca; Españ

Disturbed flow–induced Gs-mediated signaling protects against endothelial inflammation and atherosclerosis

Atherosclerosis develops preferentially in areas of the arterial system, in which blood flow is disturbed. Exposure of endothelial cells to disturbed flow has been shown to induce inflammatory signaling, including NF-κB activation, which leads to the expression of leukocyte adhesion molecules and chemokines. Here, we show that disturbed flow promotes the release of adrenomedullin from endothelial cells, which in turn activates its Gs-coupled receptor calcitonin receptor–like receptor (CALCRL). This induces antiinflammatory signaling through cAMP and PKA, and it results in reduced endothelial inflammation in vitro and in vivo. Suppression of endothelial expression of Gαs, the α subunit of the G-protein Gs; CALCRL; or adrenomedullin leads to increased disturbed flow–induced inflammatory signaling in vitro and in vivo. Furthermore, mice with induced endothelial-specific deficiency of Gαs, CALCRL, or adrenomedullin show increased atherosclerotic lesions. Our data identify an antiinflammatory signaling pathway in endothelial cells stimulated by disturbed flow and suggest activation of the endothelial adrenomedullin/CALCRL/Gs system as a promising approach to inhibit progression of atherosclerosis

Single-cell profiling reveals heterogeneity and functional patterning of GPCR expression in the vascular system

G-protein-coupled receptor (GPCR) expression is extensively studied in bulk cDNA, but heterogeneity and functional patterning of GPCR expression in individual vascular cells is poorly understood. Here, we perform a microfluidic-based single-cell GPCR expression analysis in primary smooth muscle cells (SMC) and endothelial cells (EC). GPCR expression is highly heterogeneous in all cell types, which is confirmed in reporter mice, on the protein level and in human cells. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and we identify functionally relevant subgroups of cells that are characterized by specific GPCR patterns. We further show that dedifferentiating SMC upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Taken together, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases