Impact of Asialoglycoprotein Receptor and Mannose Receptor Deficiency on Murine Plasma N-glycome Profiles.

The asialoglycoprotein receptor (ASGPR) and the mannose receptor C-type 1 (MRC1) are well known for their selective recognition and clearance of circulating glycoproteins. Terminal galactose and N-Acetylgalactosamine are recognized by ASGPR, while terminal mannose, fucose, and N-Acetylglucosamine are recognized by MRC1. The effects of ASGPR and MRC1 deficiency on the N-glycosylation of individual circulating proteins have been studied. However, the impact on the homeostasis of the major plasma glycoproteins is debated and their glycosylation has not been mapped with high molecular resolution in this context. Therefore, we evaluated the total plasma N-glycome and plasma proteome of ASGR1 and MRC1 deficient mice. ASGPR deficiency resulted in an increase in O-acetylation of sialic acids accompanied by higher levels of apolipoprotein D, haptoglobin, and vitronectin. MRC1 deficiency decreased fucosylation without affecting the abundance of the major circulating glycoproteins. Our findings confirm that concentrations and N-glycosylation of the major plasma proteins are tightly controlled and further suggest that glycan-binding receptors have redundancy, allowing compensation for the loss of one major clearance receptor.

New insights into the therapeutic options to lower lipoprotein(a).

BACKGROUND: Elevated levels of lipoprotein(a) [Lp(a)] represent a risk factor for cardiovascular disease including aortic valve stenosis, myocardial infarction and stroke. While the patho-physiological mechanisms linking Lp(a) with atherosclerosis are not fully understood, from genetic studies that lower Lp(a) levels protect from CVD independently of other risk factors including lipids and lipoproteins. Hereby, Lp(a) has been considered an appealing pharmacological target. RESULTS: However, approved lipid lowering therapies such as statins, ezetimibe or PCSK9 inhibitors have a neutral to modest effect on Lp(a) levels, thus prompting the development of new strategies selectively targeting Lp(a). These include antisense oligonucleotides and small interfering RNAs (siRNAs) directed towards apolipoprotein(a) [Apo(a)], which are in advanced phase of clinical development. More recently, additional approaches including inhibitors of Apo(a) and gene editing approaches via CRISPR-Cas9 technology entered early clinical development. CONCLUSION: If the results from the cardiovascular outcome trials, designed to demonstrate whether the reduction of Lp(a) of more than 80% as observed with pelacarsen, olpasiran or lepodisiran translates into the decrease of cardiovascular mortality and major adverse cardiovascular events, will be positive, lowering Lp(a) will become a new additional target in the management of patients with elevated cardiovascular risk.

Disease trends over time and CD4+CCR5+ T-cells expansion predict carotid atherosclerosis development in patients with systemic lupus erythematosus.

BACKGROUND AND AIM: Patients with Systemic Lupus Erythematosus (SLE) present increased cardiovascular mortality compared to the general population. Few studies have assessed the long-term development and progression of carotid atherosclerotic plaque in SLE patients. Our aim was to investigate the association of clinical and laboratory markers of disease activity and classical cardiovascular risk factors (CVRF) with carotid atherosclerosis development in SLE patients in a prospective 5-year study. METHODS AND RESULTS: Clinical history and information on principal CVRFs were collected at baseline and after 5 years in 40 SLE patients (36 women, mean age 42 ± 9 years; 14.4 ± 7 years of mean disease duration) and 50 age-matched controls. Carotid Doppler ultrasonography was employed to quantify the atherosclerotic burden at baseline and at follow up. Clinimetrics were applied to assess SLE activity over time (SLEDAI). The association between basal circulating T cell subsets (including CD4+CCR5+; CD4+CXCR3+; CD4+HLADR+; CD4+CD45RA+RO-, CD4+CD45RO+RA- and their subsets) and atherosclerosis development was evaluated. During the 5-year follow up, 32% of SLE patients, developed carotid atherosclerosis compared to 4% of controls. Furthermore, considering SLEDAI changes over time, patients within the highest tertile were those with increased incidence of carotid atherosclerosis independently of CVRF. In addition, increased levels of CD4+CCR5+ T cells were independently associated with the development of carotid atherosclerosis in SLE patients. CONCLUSION: Serial clinical evaluations over time, rather than a single point estimation of disease activity or CVRF burden, are required to define the risk of carotid atherosclerosis development in SLE patients. Specific T cell subsets are associated with long-term atherosclerotic progression and may further be of help in predicting vascular disease progression.

Vascular pentraxin 3 controls arterial thrombosis by targeting collagen and fibrinogen induced platelets aggregation.

AIM: The long pentraxin PTX3 plays a non-redundant role during acute myocardial infarction, atherosclerosis and in the orchestration of tissue repair and remodeling during vascular injury, clotting and fibrin deposition. The aim of this work is to investigate the molecular mechanisms underlying the protective role of PTX3 during arterial thrombosis. METHODS AND RESULTS: PTX3 KO mice transplanted with bone marrow from WT or PTX3 KO mice presented a significant reduction in carotid artery blood flow following FeCl3 induced arterial thrombosis (-80.36±11.5% and -95.53±4.46%), while in WT mice transplanted with bone marrow from either WT or PTX3 KO mice, the reduction was less dramatic (-45.55±1.37% and -53.39±9.8%), thus pointing to a protective effect independent of a hematopoietic cell's derived PTX3. By using P-selectin/PTX3 double KO mice, we further excluded a role for P-selectin, a target of PTX3 released by neutrophils, in vascular protection played by PTX3. In agreement with a minor role for hematopoietic cell-derived PTX3, platelet activation (assessed by flow cytometric expression of markers of platelet activation) was similar in PTX3 KO and WT mice as were haemostatic properties. Histological analysis indicated that PTX3 localizes within the thrombus and the vessel wall, and specific experiments with the N-terminal and the C-terminal PTX3 domain showed the ability of PTX3 to selectively dampen either fibrinogen or collagen induced platelet adhesion and aggregation. CONCLUSION: PTX3 interacts with fibrinogen and collagen and, by dampening their pro-thrombotic effects, plays a protective role during arterial thrombosis.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions.

AIM: Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases. DATA SYNTHESIS: Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Subclinical atherosclerosis is associated with Epicardial Fat Thickness and hepatic steatosis in the general population.

BACKGROUND AND AIMS: Abdominal obesity and hepatic steatosis are ectopic fat depots associated with Metabolic Syndrome (MetS). Epicardial Fat Thickness (EFT) is a newly discovered one, increasing with obesity, insulin resistance and MetS. Therefore we studied whether different ectopic fat markers, and EFT in particular, are associated with MetS and markers of subclinical cardiovascular disease. METHODS AND RESULTS: 868 subjects from the PLIC Study were included, EFT, aortic calcifications, carotid Intima-Media Thickness (c-IMT) and echocardiographic parameters were determined by ultrasound; extra-cardiac atherosclerotic lesions were defined in presence of plaques at both carotid and aortic levels. Hepatic steatosis degrees were defined according to a scoring system. Abdominal adiposity was determined using Dual X-ray Absorbimetry (DEXA). Independently from age, women showed higher EFT versus men (4.5 (0.20-9.00) mm vs 4.00 (0.10-8.00) mm, p = 0.013); EFT was thicker in post-menopausal women (independently from hormone-replacement therapy). EFT, liver steatosis and abdominal adiposity increased with MetS (p < 0.001). EFT was the only ectopic fat marker associated with cardiac dysfunction (OR = 1.340 [1.088-1.651 95% C.I., p = 0.006); liver steatosis and EFT were associated with extra-cardiac plaques (OR = 2.529 [1.328-4.819] 95% C.I., p < 0.001 and OR = 1.195 [1.008-1.299] 95% C.I., p = 0.042; respectively). On top of cardiovascular risk factors, only EFT improved the discrimination of subjects with cardiac dysfunction and atherosclerotic plaques. CONCLUSIONS: EFT is associated with left ventricular dysfunction and subclinical atherosclerosis. Our data suggest that EFT may represent an additional tool for the stratification of cardiovascular risk.

Telomere shortening over 6 years is associated with increased subclinical carotid vascular damage and worse cardiovascular prognosis in the general population.

INTRODUCTION: Leucocyte telomere length (LTL) is an important determinant of telomere function and cellular replicative capacity. The aim of the present study was to examine prospectively the associations between telomere shortening (TS) and both the progression of atherosclerosis and the incidence of cardiovascular events (CVEs). MATERIALS AND METHODS: Leucocyte telomere length was measured by quantitative polymerase chain reaction to determine the ratio of telomere length to single-copy gene (T/S) in 768 subjects (462 female and 306 male) enrolled in a large general population survey [the Progressione della Lesione Intimale Carotidea (PLIC study)]. Common carotid artery intima-media thickness was determined at baseline and after 6 years of follow-up, and the associations between TS and the progression of atherosclerosis and incidence of CVEs were evaluated. RESULTS: Mean LTL was 1.25 ± 0.92 T/S (median 1.14) at baseline and 0.70 ± 0.37 T/S (median 0.70) after 6 years of follow-up. Median 6-year LTL change was -0.46 T/S [interquartile range (IQR) -0.57 to 1.06], equating to -0.078 T/S [IQR(-0.092 to 0.176)] per year. Of note, telomere lengthening occurred in 30.4% of subjects. After adjustment for classical cardiovascular disease (CVD) risk factors (age, gender, smoking, physical activity, alcohol consumption, systolic blood pressure, glucose levels, lipid profile and therapies), TS was associated with incident subclinical carotid vascular damage [hazard ratio (HR) 5.19, 95% confidence interval (CI) 1.20-22.4, P = 0.028]. Finally, subjects in whom LTL shortened over time showed an increased risk of incident CVE, compared to those in whom LTL lengthened (HR 1.69, CI 1.02-2.78, P = 0.041). CONCLUSION: These data indicate that TS is associated with increased risk of subclinical carotid vascular damage and increased incidence of CVEs beyond CVD risk factors in the general population, whereas LTL lengthening is protective.

Pentraxin 3 (PTX3) plasma levels and carotid intima media thickness progression in the general population.

BACKGROUND AND AIM: Pentraxin 3 (PTX3) is an essential component of the humoral arm of innate immunity and, like C-reactive protein, is independently associated with the risk of developing vascular events. Aim of this study was to investigate, in two large population-based surveys, the Bruneck Study and the PLIC Study, whether PTX3 plasma levels predict the progression of common carotid artery intima-media thickness (CCA-IMT), a surrogate marker of atherosclerosis, in the general population during 5 or 6 years of follow-up. RESULTS: In the Bruneck Study, PTX3 plasma levels did not predict a faster progression of CCA-IMT either in the carotid artery or in the femoral artery. This finding was confirmed in the PLIC Study where subjects within the highest tertile of PTX3 did not show an increased progression of CCA-IMT. PTX3 plasma levels were also not associated with the fastest maximum IMT progression. In summary, in more than 2400 subjects from the general population, PTX3 plasma level is neither an independent predictor of progression of subclinical atherosclerosis in different arterial territories, including carotid and femoral arteries nor of incident cardiovascular events. CONCLUSION: These findings support the relevance of investigating the predictive value of PTX3 plasma levels only in specific settings, like overt CVD, heart failure or acute myocardial infarction.

Cardiometabolic and immune factors associated with increased common carotid artery intima-media thickness and cardiovascular disease in patients with systemic lupus erythematosus.

BACKGROUND AND AIM: Patients with systemic lupus erythematosus (SLE) have a higher prevalence of subclinical atherosclerosis and higher risk of cardiovascular (CV) events compared to the general population. The relative contribution of CV-, immune- and disease-related risk factors to accelerated atherogenesis in SLE is unclear. METHODS AND RESULTS: Fifty SLE patients with long-lasting disease (mean age 44 ± 10 years, 86% female) and 50 sex- and age-matched control subjects were studied. Common carotid artery intima-media thickness (CCA-IMT) was used as a surrogate marker of atherosclerosis. We evaluated traditional and immune- and disease-related factors, assessed multiple T-cell subsets by 10-parameter-eight-colour polychromatic flow cytometry and addressed the effect of pharmacological therapies on CCA-IMT. In SLE patients, among several cardiometabolic risk factors, only high-density lipoprotein levels (HDL) and their adenosine triphosphate-binding cassette transporter 1 (ABCA-1)-dependent cholesterol efflux capacity were markedly reduced (p < 0.01), whereas the CCA-IMT was significantly increased (p = 0.03) compared to controls. CCA-IMT correlated with systolic blood pressure, low-density lipoprotein (LDL) cholesterol and body mass index (BMI), but not with disease activity and duration. The activated CD4(+)HLA-DR(+) and CCR5(+) T-cell subsets were expanded in SLE patients. Patients under hydroxychloroquine (HCQ) therapy showed lower CCA-IMT (0.62 ± 0.08 vs. 0.68 ± 0.10 mm; p = 0.03) and better risk-factor profile and presented reduced circulating pro-atherogenic effector memory T-cell subsets and a parallel increased percentage of naïve T-cell subsets. CONCLUSION: HDL represents the main metabolic parameter altered in SLE patients. The increased CCA-IMT in SLE patients may represent the net result of a process in which 'classic' CV risk factors give a continuous contribution, together with immunological factors (CD4(+)HLA-DR(+) T cells) which, on the contrary, could contribute through flares of activity of various degrees over time. Patients under HCQ therapy present a modified metabolic profile, a reduced T-cell activation associated with decreased subclinical atherosclerosis.

High density lipoprotein cholesterol levels are an independent predictor of the progression of chronic kidney disease.

OBJECTIVES: Patients with chronic kidney disease (CKD) often present with reduced plasma HDL cholesterol (HDL-C) levels. Whether this reduction in an epiphenomenon or is involved in disease progression is unclear. The aim of this study was to investigate the relation between HDL-C levels/function and CKD progression in patients with different degrees of disease. DESIGN: A total of 176 patients with CKD [glomerular filtration rate (GFR) 50.3 ± 29.1 mL min⁻¹] were recruited and followed for up to 84 months. Lipid profile, metabolic status and kidney function were evaluated at predetermined times. Age-matched control subjects were selected from the PLIC study (n = 453). Scavenger receptor class B member 1 (SR-BI) and ATP-binding cassette transporter A1 (ABCA-1)-dependent efflux of cholesterol were measured in CKD patients and in age-matched control subjects. RESULTS: Low HDL-C levels, diabetes and hypertension were associated with reduced GFR. At follow-up, low HDL-C levels were associated with earlier entry in dialysis or doubling of the plasma creatinine level (P = 0.017); HDL-C levels were the only lipid parameter that affected the progression of CKD (hazard ratio 0.951, 95% confidence interval 0.917-0.986, P = 0.007), independently of the presence of diabetes. Only SR-BI-mediated serum cholesterol efflux was significantly reduced in the group of CKD patients with low HDL-C levels compared to the control group. CONCLUSIONS: CKD patients with low levels of plasma HDL-C have a poor prognosis. HDL functionality is also impaired in renal dysfunction. These data support the relevance of HDL in influencing CKD progression.

The zebrafish embryo derivative affects cell viability of epidermal cells: a possible role in the treatment of psoriasis.

In patients affected by psoriasis, use of a topical formula containing a derivative of zebrafish embryos was associated with reduced skin inflammation and dermal turnover, as well as a generally better outcome. In an attempt to understand the molecular mechanisms lying beyond these findings, we investigated the anti-proliferative effects of the zebrafish embryos derivative by addressing the mitochondrial function (MTT assay) and cell nuclei distribution (Hoestch staining). In cell cultures stimulated with fetal calf serum (FCS) or epidermal growth factor (EGF), the zebrafish derivative significantly inhibited cell proliferation induced by either approach, although the effect was stronger in cells stimulated with FCS. These results suggest that the zebrafish embryos derivative may dampen increased cell proliferation; this observation may be relevant to cutaneous pathologies related to altered proliferative mechanisms, including psoriasis.

MicroRNA 143-145 deficiency impairs vascular function.

MicroRNAs are required for vascular smooth muscle growth, differentiation and function. MiR143-145 modulates cytoskeletal dynamics and acquisition of the contractile phenotype by smooth muscle cells. Lack of this miRNA cluster results in decreased blood pressure and reduced vasocontraction. As all these observations point to a key role for miR143-145 in the vasculature, we investigated whether miR143-145 deficiency is associated with impaired vascular tone. Vasocontraction was assessed in isolated aortic rings from miR143-145 KO and wild type animals incubated with increasing concentrations of phenylephrine (10(-9)M to 10(-5)M) or KCl 0.3M. In both cases, aortic vessel contraction was dramatically reduced in miR143-145 KO animals compared to controls. Next, aortic rings were pre-contracted with phenylephrine (EC60: 10(-7)M) and concentration responses for acetylcholine were obtained. A significantly reduced vasodilation was observed in miR143-145 KO animals compared to controls and similar results were obtained when an exogenous donor of nitric oxide (sodium nitroprusside) was used. Endothelial nitric oxide synthase or guanylate cyclase mRNA expression were not different between the animal groups thus suggesting to investigate the effect of other vasodilators. Isoprenaline mediated vasodilation was significantly reduced in miR143-145 KO animals compared to controls in the absence or in the presence of the guanylate cyclase inhibitor ODQ (10(-4)M), suggesting that also beta adrenergic vasodilation is impaired following miR143-145 deficiency. Finally, the effect of a stable mimetic prostacyclin, namely iloprost, was investigated and again a reduced vasodilation was observed in miR143-145 KO animals. MiR143-145 deficiency is associated not only with altered vasocontraction but also with impaired vasodilation, which probably reflects the impaired VSMC differentiation phenotype reported in miR143-145 KO animals.

Monocarboxylate transporter 1 deficiency impacts CD8+ T lymphocytes proliferation and recruitment to adipose tissue during obesity.

Lactate sits at the crossroad of metabolism, immunity, and inflammation. The expression of cellular lactate transporter MCT1 (known as Slc16a1) increases during immune cell activation to cope with the metabolic reprogramming. We investigated the impact of MCT1 deficiency on CD8+ T cell function during obesity-related inflammatory conditions. The absence of MCT1 impaired CD8+ T cell proliferation with a shift of ATP production to mitochondrial oxidative phosphorylation. In Slc16a1 f/f Tcell cre mice fed a high-fat diet, a reduction in the number of CD8+ T cells, which infiltrated epididymal visceral adipose tissue (epiWAT) or subcutaneous adipose tissue, was observed. Adipose tissue weight and adipocyte area were significantly reduced together with downregulation of adipogenic genes only in the epiWAT. Our findings highlight a distinct effect of MCT1 deficiency in CD8+ T cells in the crosstalk with adipocytes and reinforce the concept that targeting immunometabolic reprogramming in lymphocyte could impact the immune-adipose tissue axis in obesity.

Proprotein convertase subtilisin/kexin type 9 (PCSK9): from structure-function relation to therapeutic inhibition.

AIMS: This short review aims at summarizing the current information on Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) structure and function focusing also on the therapeutic possibilities based on the inhibition of this protein. DATA SYNTHESIS: PCSK9 has been recently discovered as the third gene involved in autosomal dominant hypercholesterolemia. PCSK9 binds and favors degradation of the low-density lipoprotein receptor (LDLR) and thereby modulates the plasma levels of LDL-cholesterol (LDL-C). Some of the natural occurring PCSK9 mutations increase the protein function (gain of function) and cause hypercholesterolemia, whereas loss of function mutations associate with hypocholesterolemia. Since the loss of a functional PCSK9 in humans is not associated with apparent deleterious effects, this protease is an attractive target for the development of lowering plasma LDL-C agents, either alone or in combination with statins. CONCLUSION: Inhibition of PCSK9 is emerging as a novel strategy for the treatment of hypercholesterolemia and data obtained from pre-clinical studies show that use of monoclonal antibodies, antisense oligonucleotides and short interfering RNA are effective in reducing LDL-C, clinical studies, accompanied by a better understanding of PCSK9 biology, are now necessary to address whether these new compounds will have a future in clinical practice.

Metabolic adaptations of cells at the vascular-immune interface during atherosclerosis.

Metabolic reprogramming is a physiological cellular adaptation to intracellular and extracellular stimuli that couples to cell polarization and function in multiple cellular subsets. Pathological conditions associated to nutrients overload, such as dyslipidaemia, may disturb cellular metabolic homeostasis and, in turn, affect cellular response and activation, thus contributing to disease progression. At the vascular/immune interface, the site of atherosclerotic plaque development, many of these changes occur. Here, an intimate interaction between endothelial cells (ECs), vascular smooth muscle cells (VSMCs) and immune cells, mainly monocytes/macrophages and lymphocytes, dictates physiological versus pathological response. Furthermore, atherogenic stimuli trigger metabolic adaptations both at systemic and cellular level that affect the EC layer barrier integrity, VSMC proliferation and migration, monocyte infiltration, macrophage polarization, lymphocyte T and B activation. Rewiring cellular metabolism by repurposing "metabolic drugs" might represent a pharmacological approach to modulate cell activation at the vascular immune interface thus contributing to control the immunometabolic response in the context of cardiovascular diseases.

Plasma adiponectin levels in chronic kidney disease patients: relation with molecular inflammatory profile and metabolic status.

BACKGROUND AND AIM: Adiponectin (ADPN) exerts anti-inflammatory and cardio protective effects and is associated with decreased cardiovascular risk, however its role in patients with chronic kidney disease is unclear. METHODS AND RESULTS: We investigated the correlation between plasma ADPN levels, the progression of CVD and CKD and the inflammatory gene expression profile of peripheral blood mononuclear cells in patients from the NephroPLIC study (a prospective study aimed at addressing the progression of cardiovascular damage in relation to kidney dysfunction). Plasma ADPN levels were directly correlated with age, HDL-C and creatinine, and inversely with BMI, triglycerides and glomerular filtration rate (GFR). Multiple regression analysis identified plasma creatinine and HDL as the independent factors associated with ADPN plasma levels. In peripheral blood mononuclear cells (PBMC), the mRNA expression of MCP-1, CD40, Cox-2, TLR4, PAI-1, TNF alpha, resistin and RAGE was up-regulated in the group with higher GFR and higher ADPN plasma levels compared to that with low GFR and ADPN plasma levels. Patients with similar GFR values showed no differences in the gene expression profile of PBMC although ADPN levels were associated with decreased CRP and IL-6 plasma levels and decreased IMT and heart left ventricular mass. CONCLUSION: In CKD patients who are not in dialysis ADPN plasma levels are associated with a reduced renal excretory function, but correlate inversely with the determinants of the metabolic syndrome such as glucose, triglycerides and BMI, and directly with HDL. Furthermore, in patients with a similar degree of renal impairment, ADPN plasma levels are associated with a better cardiometabolic profile, despite no significant difference being observed in the gene expression pattern of PBMC.

Lysosomal Acid Lipase: From Cellular Lipid Handler to Immunometabolic Target.

Lysosomal acid lipase (LAL) hydrolyzes cholesteryl esters (CEs) and triglycerides (TGs) to free cholesterol (FC) and free fatty acids (FFAs), which are then used for metabolic purposes in the cell. The process also occurs in immune cells that adapt their metabolic machinery to cope with the different energetic requirements associated with cell activation, proliferation, and polarization. LAL deficiency (LALD) causes severe lipid accumulation and affects the immunometabolic signature in animal models. In humans, LAL deficiency is associated with a peculiar clinical immune phenotype, secondary hemophagocytic lymphohistiocytosis. These observations suggest that LAL might play an important role in cellular immunometabolic modulation, and availability of an effective enzyme replacement strategy makes LAL an attractive target to rewire the metabolic machinery of immune cells beyond its role in controlling cellular lipid metabolism.

Plasma resistin levels correlate with determinants of the metabolic syndrome.

OBJECTIVE: The role of resistin in insulin sensitivity and obesity is controversial. Some authors suggest that increased serum resistin levels are associated with obesity, visceral fat, insulin resistance, type 2 diabetes and inflammation, while others failed to observe such correlations. The aim of the present study was to investigate the relationship of plasma resistin levels with markers of the metabolic syndrome and atherosclerosis in a large population-based study. DESIGN AND PATIENTS: Plasma resistin levels were determined in 1090 subjects free of any medication selected from the PLIC study (designed to verify the presence of atherosclerotic lesions and progression intima-media thickness (IMT) in the common carotid artery in the general population) and related to the presence of obesity, metabolic syndrome, metabolic abnormalities, cardiovascular risk, and progression of IMT. RESULTS: Plasma resistin levels were highly positively correlated with triglycerides, waist circumference, waist/hip ratio, systolic blood pressure, and ApoAI/ApoB ratio, while they were inversely correlated with high density lipoprotein and ApoAI levels. This finding was gender specific (mainly in women). Plasma resistin levels were significantly higher in women with the metabolic syndrome compared with controls (4.90 (0.24) ng/ml vs 3.90 (0.11) ng/ml; P<0.01), while no difference was observed in obese subjects. Finally, plasma resistin levels were significantly correlated with cardiovascular risk calculated according to the Framingham algorithm (P<0.01). CONCLUSION: Plasma resistin levels are increased in presence of the metabolic syndrome and are associated with increased cardiovascular risk.

Niemann-Pick C1-Like 1 (NPC1L1) Inhibition and Cardiovascular Diseases.

Circulating levels of cholesterol are derived from either endogenous production or intestinal absorption of dietary and biliary cholesterol. Niemann-Pick C1-Like 1 (NPC1L1) is a transmembrane protein that plays a key role in the intestinal absorption of cholesterol by facilitating its uptake through vesicular endocytosis. NPC1L1 is the molecular target of ezetimibe which binds its extracellular loop and inhibits sterol absorption without affecting the absorption of other molecules. Ezetimibe significantly reduces plasma levels of total and low density lipoprotein cholesterol (LDL-C) as monotherapy or when added to statins, the association with a low dose of statin is of particular interest for patients experiencing statin-related side effects. The recent results of the IMPROVE-IT study, which evaluated the cardiovascular effect of ezetimibe added to simvastatin therapy in subjects who had had an acute coronary syndrome and with LDL-C levels within the recommended range, showed that a further LDL-C lowering reduced the incidence of cardiovascular events. To date, ezetimibe represents the only inhibitor of NPC1L1 available for clinical use, however, novel aminoß- lactam ezetimibe derivatives have been synthesized and their efficacy to inhibit NPC1L1 protein and decrease plasma cholesterol levels is under evaluation.

Assimilation of LDL by experimental tumours in mice.

We have studied the uptake of 125I-labelled low-density lipoprotein (LDL) by seven experimental murine tumours in vivo. Four tumours (Lewis Lung carcinoma, B-16, MS-2 and Colon 26) showed a higher relative uptake of lipoprotein as compared to the liver, two (L-1210 and P-388) had a very low lipoprotein uptake, while lipoprotein uptake by tumour M5 was similar to that of the liver. The data was confirmed by tracing tissue uptake of lipoproteins using [14C]sucrose-labeled LDL. These in vivo findings correlated well with the in vitro specific binding of 125I-beta-VLDL to membranes prepared from tumours, thus suggesting that the expression of the LDL receptor in the tumours is related to the in vivo uptake of lipoprotein. Further analysis of the LDL receptor by ligand blotting showed that the tumor receptor has several of the liver LDL receptor characteristics (including apparent Mr, sensitivity to proteinases, and Ca2+ requirement of lipoprotein binding). In summary, our data show that experimental murine tumours express the LDL receptor and suggest that the high relative in vivo uptake of LDL is determined by the elevated LDL-receptor expression in the tumours.