LRP5 associates with specific subsets of macrophages: Molecular and functional effects.

Innate and acquired immunity is involved in the progression of atherosclerosis. The molecular mechanisms ruling monocyte to macrophage (Mø) differentiation are not yet fully understood. Different subtypes of plaque macrophages that have differentiated from monocytes recruited from circulating blood, have been characterized based on surface epitopes. We have recently shown that LRP5, a member of the LDL receptor superfamily supporting Wnt signalling, has an important role in monocyte to macrophage differentiation. The aim of this study was to investigate whether the CD16- and CD16+ macrophage subsets found in human atherosclerotic plaques have a differential LRP5 expression/function and Wnt signalling potential. We show for the first time that LRP5 expression is significantly higher in human CD16+Mø derived from CD14(+)CD16(+) monocytes than in CD16-Mø macrophages derived from CD14(+)CD16(-) monocytes. LRP5 is not found in human healthy vessel or arterial intimal thickening but is found in advanced human atherosclerotic lesions co-localizing only with the CD16+Mø macrophage subset. LRP5 expressing macrophages infiltrate the deep layers of atherosclerotic plaques towards the intima-media boundaries showing increased migratory activity and higher phagocytic activity. The equivalent for human patrolling CD14(+)CD16(+) monocytes in mice, CD115(+)GR1(low) monocytes, also show an increased expression of LRP5. In summary, classical CD14(+)CD16(-)monocytes that differentiate into CD16-Mø do not express LRP5. Instead, human monocytes expressing LRP5 differentiate into CD16+Mø antiinflammatory macrophages. These antiinflammatory macrophages are found in advanced atherosclerotic human plaques. Thus LRP5 is a signature of the anti-inflammatory defensive phenotype of macrophages.

Low density lipoprotein receptor-related protein 1 is upregulated in epicardial fat from type 2 diabetes mellitus patients and correlates with glucose and triglyceride plasma levels.

Lipoprotein receptor expression plays a crucial role in the pathophysiology of adipose tissue in in vivo models of diabetes. However, there are no studies in diabetic patients. The aims of this study were to analyze (a) low-density lipoprotein receptor-related protein 1 (LRP1) and very low-density lipoprotein receptor (VLDLR) expression in epicardial and subcutaneous fat from type 2 diabetes mellitus compared with nondiabetic patients and (b) the possible correlation between the expression of these receptors and plasmatic parameters. Adipose tissue biopsy samples were obtained from diabetic (n = 54) and nondiabetic patients (n = 22) undergoing cardiac surgery before the initiation of cardiopulmonary bypass. Adipose LRP1 and VLDLR expression was analyzed at mRNA level by real-time PCR and at protein level by Western blot analysis. Adipose samples were also subjected to lipid extraction, and fat cholesterol ester, triglyceride, and free cholesterol contents were analyzed by thin-layer chromatography. LRP1 expression was higher in epicardial fat from diabetic compared with nondiabetic patients (mRNA 17.63 ± 11.37 versus 7.01 ± 4.86; P = 0.02; protein 11.23 ± 7.23 versus 6.75 ± 5.02, P = 0.04). VLDLR expression was also higher in epicardial fat from diabetic patients but only at mRNA level (231.25 ± 207.57 versus 56.64 ± 45.64, P = 0.02). No differences were found in the expression of LRP1 or VLDLR in the subcutaneous fat from diabetic compared with nondiabetic patients. Epicardial LRP1 and VLDLR mRNA overexpression positively correlated with plasma triglyceride levels (R(2) = 0.50, P = 0.01 and R(2) = 0.44, P = 0.03, respectively) and epicardial LRP1 also correlated with plasma glucose levels (R(2) = 0.33, P = 0.03). These results suggest that epicardial overexpression of certain lipoprotein receptors such as LRP1 and VLDLR expression may play a key role in the alterations of lipid metabolism associated with type 2 diabetes mellitus.

Efecto de la LDL modificada en la expresión de adipofilina en macrófagos y células musculares lisas de la pared vascular. Implicaciones para el desarrollo de arteriosclerosis / Effect of modified LDL in the expression of adipocyte differentiation-related protein in macrophages and vascular smooth muscle cells. Implications for atherosclerosis progression

Objetivo: Analizar si la unión e interiorización de la LDL modificada por agregación (LDLag) puede inducir la expresión de la proteina adipofilina (ADRP), un marcador de acumulación lipídica, en las células musculares lisas de la pared vascular (CMLV) y macrófagos humanos. Resultados: La LDLag induce la sobreexpresión de ADRP tanto a nivel de ARNm (PCR tiempo real) como a nivel de proteina («western blot») en CMLV (ARNm: 3.06-veces; proteina: 8.58-veces) y también en macrófagos (ARNm: 3.5-veces; proteina: 3.71-veces). Los estudios immunohistoquímicos evidenciaron una alta colocalización entre ADRP y CMLV y también entre ADRP y macrófagos en placas ateroscleróticas avanzadas ricas en lípido. Conclusiones: La captación de LDLag mediante el receptor lipoproteíco LRP1 juega un papel primordial en la formación de células espumosas a partir de macrófagos y de CMLV y, por tanto, en la progresión de la lesión aterosclerótica (AU)

Aims: The objectives of this work were to analyze whether aggregated LDL (agLDL) uptake modulates ADRP expression levels in human vascular smooth muscle cells (VSMC) and macrophages (HMDM). Methods and Results: AgLDL strongly upregulated ADRP mRNA (Real-time PCR) and protein expression (western blot) in human VSMC (mRNA: by 3.06-fold; protein: 8.58-fold) and HMDM (mRNA: by 3.5-fold; protein: by 3.71-fold).. Immunohystochemical studies evidence a high colocolocalization between ADRP/macrophages and ADRP/VSMC in advanced lipid-enriched atherosclerotic plaques. Conclusions:These results demonstrate that agLDL-LRP1 engagement induces ADRP overexpression in both HMDM and human VSMC. ADRP is highly expressed in advanced lipid-enriched human atherosclerotic plaques. Therefore, LRP1-mediated agLDL uptake might play a pivotal role on vascular foam cell formation and atherosclerotic plaque progression (AU)

Adipocyte differentiation-related protein is induced by LRP1-mediated aggregated LDL internalization in human vascular smooth muscle cells and macrophages.

Aggregated LDL (agLDL) is internalized by LDL receptor-related protein (LRP1) in vascular smooth muscle cells (VSMCs) and human monocyte-derived macrophages (HMDMs). AgLDL is, therefore, a potent inducer of massive intracellular cholesteryl ester accumulation in lipid droplets. The adipocyte differentiation-related protein (ADRP) has been found on the surface of lipid droplets. The objectives of this work were to analyze whether agLDL uptake modulates ADRP expression levels and whether the effect of agLDL internalization on ADRP expression depends on LRP1 in human VSMCs and HMDMs. AgLDL strongly upregulates ADRP mRNA (real-time PCR) and protein expression (Western blot) in human VSMCs (mRNA: by 3.06-fold; protein: 8.58-fold) and HMDMs (mRNA: by 3.5-fold; protein: by 3.71-fold). Treatment of VSMCs and HMDMs with small anti-LRP1-interfering RNA (siRNA-LRP1) leads to specific inhibition of LRP1 expression. siRNA-LRP1 treatment significantly reduced agLDL-induced ADRP overexpression in HMDMs (by 69%) and in VSMCs (by 53%). Immunohystochemical studies evidence a colocolocalization between ADRP/macrophages and ADRP/VSMCs in advanced lipid-enriched atherosclerotic plaques. These results demonstrate that agLDL-LRP1 engagement induces ADRP overexpression in both HMDMs and human VSMCs and that ADRP is highly expressed in advanced lipid-enriched human atherosclerotic plaques. Therefore, LRP1-mediated agLDL uptake might play a pivotal role in vascular foam cell formation.

[Relationship between cholesterol and fibrinogen in two populations of different geographical location of Catalonia]. / Relación entre colesterol y fibrinógeno en dos poblaciones de distinta localización geográfica de Cataluña.

OBJECTIVES: Verification of the following in two different geographical location populations (seashore and mountain) with cardiovascular symptomatology: 1) the prevalence of hyperfibrinogenemia and possible correlation with cholesterolemia; 2) the differences between both populations in the profiles of these parameters. DESIGN: Cross-sectional descriptive study. CONTEXT: Primary Care. PARTICIPANTS: Three hundred and seventy five patients who went to two hospitals between May 1995 and July 1998. In the seashore center 256 patients and in the mountain center 119 patients. MAIN MEASUREMENTS: Clinical history and analytical parameters. Fibrinogen (FBG), indirect prothrombin time, enzymatic cholesterol (CLT) Utachi 717. The patients were sorted out into 4 groups: 1) high FBG > 300 mg/dl and high CLT > 240 mg/dl; 2) high FBG > 300 and low CLT < 240; 3) low FBG < 300 and high CLT > 240, and 4) low FBG < 300 and low CLT < 240. RESULTS: Levels of FBG: homogeneous between groups 1 and 2 (high) and 3 and 4 (low), and different between upper and lower groups. Cholesterol showed the same behavior. Group 1 with a similar number of patients in mountain and seashore (40% and 41%). Group 2 with 42.8% of patients from mountain and 26.9% from seashore. Groups 3 and 4 are presented with lower percentages. We did not find correlation between the levels of FBG and those of CLT. CONCLUSIONS: Predominance of patients with high FBG and normal CLT (group 2) in the mountain cohort, in contrast with a higher prevalence of normal FBG and high CLT (group 3) in the seashore cohort. In participants with normal levels or with high risk the variations of the FBG were not dependent nor related to those of CLT.