Decreased low-density lipoprotein receptor-related protein 1 expression in pro-inflammatory monocytes is associated with subclinical atherosclerosis.

Subclinical atherosclerosis (SCA) occurs in asymptomatic individuals. Blood peripheral monocytes are involved in the development of atherosclerosis. Circulating monocytes acquire pro-inflammatory profiles, and they are involved in the early stages of atherosclerosis development. Low-density lipoprotein Receptor-related Protein 1 (LRP1) is expressed in monocytes, mainly in classical and intermediate subsets. Although LRP1 is highly expressed in macrophages and vascular smooth muscle cells (VSMCs) in atherosclerotic plaque formation, its expression in circulating monocytes has not been studied in SCA. The aim of this study was to characterize the LRP1 expression level in circulating monocytes of individuals with SCA and compared with individuals with low (LR) and intermediate (IR) risk of cardiovascular diseases, both without evidence of atherosclerotic lesions in carotid and coronary arteries. LRP1 and additional markers (CD11b, CD11c, and CD36) at cell surface of monocytes were analyzed by flow cytometry assays, whereas LRP1 and pro-inflammatory factors gene expressions were measured in isolated monocytes by quantitative RT-PCRs. Both LRP1 protein and LRP1 mRNA were significantly reduced in monocytes in SCA and IR respect to LR. Conversely, CD36, CD11b, and CD11c monocytic markers showed no significant changes between the different study groups. Finally, increased gene expressions of TNF-α and IL-1ß were detected in monocytes of SCA, which were associated with decreased LRP1 expression at the cell surface in total monocytes. In summary, we propose that the decreased LRP1 expression at cell surface in total monocytes with pro-inflammatory profile is associated with the development of atherosclerosis in asymptomatic individuals.

IGF-1R Regulates the Extracellular Level of Active MMP-2, Pathological Neovascularization, and Functionality in Retinas of OIR Mouse Model.

In ischemic proliferative diseases such as retinopathies, persistent hypoxia leads to the release of numerous neovascular factors that participate in the formation of abnormal vessels and eventually cause blindness. The upregulation and activation of metalloproteinases (MMP-2 and MMP-9) represent a final common pathway in this process. Although many regulators of the neovascular process have been identified, the complete role of the insulin-like growth factor 1 (IGF-1) and its receptor (IGF-1R) appears to be significantly more complex. In this study, we used an oxygen-induced retinopathy (OIR) mouse model as well as an in vitro model of hypoxia to study the role of MMP-2 derived from Müller glial cells (MGCs) and its relation with the IGF-1/IGF-1R system. We demonstrated that MMP-2 protein expression increased in P17 OIR mice, which coincided with the active phase of the neovascular process. Also, glutamine synthetase (GS)-positive cells were also positive for MMP-2, whereas IGF-1R was expressed by GFAP-positive cells, indicating that both proteins were expressed in MGCs. In addition, in the OIR model a single intravitreal injection of the IGF-1R blocking antibody (αIR3) administered at P12 effectively prevented pathologic neovascularization, accelerated physiological revascularization, and improved retinal functionality at P17. Finally, in MGC supernatants, the blocking antibody abolished the IGF-1 effect on active MMP-2 under normoxic and hypoxic conditions without affecting the extracellular levels of pro-MMP-2. These results demonstrate, for the first time, that the IGF-1/IGF-1R system regulates active MMP-2 levels in MGCs, thus contributing to MEC remodeling during the retinal neovascular process.

Association between cardiovascular disease risk scores and subclinical atherosclerosis prevalence in non-elderly adult patients from Argentina.

The goal of our study was to use statistical analysis to try to associate cardiovascular disease (CVD) risk scores and the observed prevalence of subclinical atherosclerosis (SA) in a non-elderly adult local population. An observational cross-sectional study was carried out (143 male and 131 female) on non-elderly adults (20-59 years). CVD risk scores included Framingham Risk Scores for 10-year hard (FRS 10 H), 30-year lipid hard or CVD (FRS 30 L H or FRS 30 L CVD), 30 year-body mass index hard or CVD (FRS 30 BMI H or FRS 30 BMI CVD) and Pooled Cohort Risk Equations for either 10 years (PCE 10) or lifetime (PCE LT). The Carotid Ultrasound (CU) study was performed and the Coronary Artery Calcium (CAC) score were obtained to assess SA. The Receiving Operating Characteristic (ROC) curve analysis followed by Youden's index was used to evaluate and adjust the stratification of CVD risk scores. SA was detected in 32.4% of individuals. The risk scores that showed the biggest areas under the ROC curve were FRS 30 L (H and CVD). When the cut-off values for these CVD risk scores were adjusted, the FRS 30 L H increased the negative predictive value for the low risk group from 87.7 to 97.0% and the FRS 30 L CVD increased the positive predictive values for the high risk group from 69.7 to 85.7%. The CVD risk stratification of non-elderly adults using FRS 30 L H and FRS 30 L CVD may be a useful tool for selecting candidate patients for diagnostic imaging studies that assess their SA prevalence.

Activated α2 -Macroglobulin Induces Mesenchymal Cellular Migration Of Raw264.7 Cells Through Low-Density Lipoprotein Receptor-Related Protein 1.

Distinct modes of cell migration contribute to diverse types of cell movements. The mesenchymal mode is characterized by a multistep cycle of membrane protrusion, the formation of focal adhesion, and the stabilization at the leading edge associated with the degradation of extracellular matrix (ECM) components and with regulated extracellular proteolysis. Both α2 -Macroglobulin (α2 M) and its receptor, low density lipoprotein receptor-related protein 1 (LRP1), play important roles in inflammatory processes, by controlling the extracellular activity of several proteases. The binding of the active form of α2 M (α2 M*) to LRP1 can also activate different signaling pathways in macrophages, thus inducing extracellular matrix metalloproteinase-9 (MMP-9) activation and cellular proliferation. In the present study, we investigated whether the α2 M*/LRP1 interaction induces cellular migration of the macrophage-derived cell line, Raw264.7. By using the wound-scratch migration assay and confocal microscopy, we demonstrate that α2 M* induces LRP1-mediated mesenchymal cellular migration. This migration exhibits the production of enlarged cellular protrusions, MT1-MMP distribution to these leading edge protrusions, actin polymerization, focal adhesion formation, and increased intracellular LRP1/ß1-integrin colocalization. Moreover, the presence of calphostin-C blocked the α2 M*-stimulated cellular protrusions, suggesting that the PKC activation is involved in the cellular motility of Raw264.7 cells. These findings could constitute a therapeutic target for inflammatory processes with deleterious consequences for human health, such as rheumatoid arthritis, atherosclerosis and cancer. J. Cell. Biochem. 118: 1810-1818, 2017. © 2016 Wiley Periodicals, Inc.

Standardized flow cytometry assay for identification of human monocytic heterogeneity and LRP1 expression in monocyte subpopulations: decreased expression of this receptor in nonclassical monocytes.

In this article, we present a flow cytometry assay by which human blood monocyte subpopulations-classical (CD14(++) CD16(-)), intermediate (CD14(++) CD16(+)), and nonclassical (CD14(+) CD16(++)) monocytes-can be determined. Monocytic cells were selected from CD45(+) leukocyte subsets by differential staining of the low-density lipoprotein receptor-related protein 1 (LRP1), which allows reducing the spill-over of natural killer cells and granulocytes into the CD16(+) monocyte gate. Percentages of monocyte subpopulations established by this procedure were significantly comparable with those obtained by a well-standardized flow cytometry assay based on the HLA-DR monocyte-gating strategy. We also demonstrated that LRP1 is differentially expressed at cell surface of monocyte subpopulations, being significantly lower in nonclassical monocytes than in classical and intermediate monocytes. Cell surface expression of LRP1 accounts for only 20% of the total cellular content in each monocyte subpopulation. Finally, we established the within-individual biological variation (bCV%) of circulating monocyte subpopulations in healthy donors, obtaining values of 21%, 20%, and 17% for nonclassical, intermediate, and classical monocytes, respectively. Similar values of bCV% for LRP1 measured in each monocyte subpopulation were also obtained, suggesting that its variability is mainly influenced by the intrinsic biological variation of circulating monocytes. Thus, we conclude that LRP1 can be used as a third pan-monocytic marker together with CD14 and CD16 to properly identify monocyte subpopulations. The combined determination of monocyte subpopulations and LRP1 monocytic expression may be relevant for clinical studies of inflammatory processes, with special interest in atherosclerosis and cardiovascular disease.