Neutral lipid alterations in human herpesvirus 8-infected HUVEC cells and their possible involvement in neo-angiogenesis.

BACKGROUND: Human Herpesvirus 8 (HHV8), the causative agent of Kaposi's sarcoma, induces an intense modification of lipid metabolism and enhances the angiogenic process in endothelial cells. In the present study, neutral lipid (NL) metabolism and angiogenesis were investigated in HHV8-infected HUVEC cells. The viral replication phases were verified by rtPCR and also by K8.1 and LANA immunostaining. RESULTS: Lipid droplets (Nile Red) were higher in all phases and NL staining (LipidTOX) combined with viral-antigen detection (immunofluorescence) demonstrated a NL content increase in infected cells. In particular, triglyceride synthesis increases in the lytic phase, whereas cholesteryl ester synthesis rises in the latent one. Moreover, the inhibition of cholesterol esterification reduces neo-tubule formation mainly in latently infected cells. CONCLUSIONS: We suggest that a reprogramming of cholesteryl ester metabolism is involved in regulating neo-angiogenesis in HHV8-infected cells and plays a likely role in the high metastatic potential of derived-tumours.

Role of HDL in cholesteryl ester metabolism of lipopolysaccharide-activated P388D1 macrophages.

Infections share with atherosclerosis similar lipid alterations, with accumulation of cholesteryl esters (CEs) in activated macrophages and concomitant decrease of cholesterol-HDL (C-HDL). Yet the precise role of HDL during microbial infection has not been fully elucidated. Activation of P388D1 by lipopolysaccharide (LPS) triggered an increase of CEs and neutral lipid contents, along with a remarkable enhancement in 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-HDL uptake. Similar results were found in human monocyte-derived macrophages and monocytes cocultured with phytohemagglutinin-activated lymphocytes. Inhibition of cholesterol esterification with Sandoz-58035 resulted in 80% suppression of CE biosynthesis in P388D1. However, only a 35% decrease of CE content, together with increased scavenger receptor class B member 1 (SR-B1) protein expression, was found after 72 h and thereafter up to 16 passages of continuous ACAT suppression. Chronic inhibition blunted the effect of LPS treatment on cholesterol metabolism, increased the ratio of free cholesterol/CE content and enhanced interleukin 6 secretion. These results imply that, besides de novo biosynthesis and acquisition by LDL, HDL contributes probably through SR-B1 to the increased CE content in macrophages, partly explaining the low levels of C-HDL during their activation. Our data suggest that in those conditions where more CEs are required, HDL rather than removing, may supply CEs to the cells.

Sheep cheese naturally enriched in α-linolenic, conjugated linoleic and vaccenic acids improves the lipid profile and reduces anandamide in the plasma of hypercholesterolaemic subjects.

Intake of dairy fat has long been considered as a risk factor for CVD. Pasture and dietary lipid supplementation have been reported to be reliable strategies in ruminant nutrition, in order to increase the content of α-linolenic acid (ALA), conjugated linoleic acid (CLA) and vaccenic acid (VA), and decrease SFA in milk fat. In the present study, we aimed at verifying whether consumption of a sheep cheese, naturally enriched in ALA, CLA and VA, would modify the plasma lipid and endocannabinoid profiles in mildly hypercholesterolaemic subjects. A total of forty-two adult volunteers (nineteen males and twenty-three females) with diagnosed mildly hypercholesterolaemia (total cholesterol 5·68-7·49 mmol/l) were randomly assigned to eat 90 g/d of a control or enriched cheese for 3 weeks, with a cross-over after 3 weeks of washout. Plasma lipids, endocannabinoids, adipokines and inflammatory markers were measured. The intake of enriched cheese significantly increased the plasma concentrations of CLA, VA, the n-3 fatty acids ALA and EPA, and more remarkably decreased that of the endocannabinoid anandamide. LDL-cholesterol decreased significantly (7%). No changes were detected in the levels of inflammatory markers; however, a significant correlation was found between the plasma levels of anandamide and leptin. The control cheese modified none of the parameters measured. The results obtained do not support the view that intake of dairy fat is detrimental to hypercholesterolaemic subjects. Indeed, they show that a naturally enriched cheese possesses beneficial properties, since it ameliorates the plasma lipid profile, and more remarkably reduces endocannabinoid biosynthesis.

A lipoprotein source of cholesteryl esters is essential for proliferation of CEM-CCRF lymphoblastic cell line.

Tumour are characterised by a high content of cholesteryl esters (CEs) stored in lipid droplets purported to be due to a high rate of intracellular esterification of cholesterol. To verify whether and which pathways involved in CE accumulation are essential in tumour proliferation, the effect of CE deprivation, from both exogenous and endogenous sources, on CEM-CCRF cells was investigated. Cholesterol synthesis, esterification and content, low-density lipoprotein (LDL) binding and high-density lipoprotein (HDL)-CE uptake were evaluated in cultured in both conventional and delipidated bovine serum with or without oleic or linoleic acids, cholesteryl oleate, LDL and HDL. High content of CEs in lipid droplets in this cell line was due to esterification of both newly synthesised cholesterol and that obtained from hydrolysis of LDL; moreover, a significant amount of CE was derived from HDL-CE uptake. Cell proliferation was slightly affected by either acute or chronic treatment up to 400 µM with Sz-58035, an acyl-cholesteryl cholesterol esterification inhibitor (ACAT); although when the enzyme activity was continuously inhibited, CE content in lipid droplets was significantly higher than those in control cells. In these cells, analysis of intracellular and medium CEs revealed a profile reflecting the characteristics of bovine serum, suggesting a plasma origin of CE molecules. Cell proliferation arrest in delipidated medium was almost completely prevented in the first 72 h by LDL or HDL, although in subsequent cultures with LDL, it manifested an increasing mortality rate. This study suggests that high content of CEs in CEM-CCRF is mainly derived from plasma lipoproteins and that part of CEs stored in lipid droplets are obtained after being taken up from HDL. This route appears to be up-regulated according to cell requirements and involved in low levels of c-HDL during cancer. Moreover, the dependence of tumour cells on a source of lipoprotein provides a novel impetus in developing therapeutic strategies for use in the treatment of some tumours.

IL-6 serum levels and production is related to an altered immune response in polycystic ovary syndrome girls with insulin resistance.

Polycystic ovarian syndrome (PCOS) is frequently characterized by obesity and metabolic diseases including hypertension, insulin resistance, and diabetes in adulthood, all leading to an increased risk of atherosclerosis. The present study aimed to evaluate serum and production of inflammatory markers in adolescent Sardinian PCOS. On the basis of HOMA findings, patients were divided into noninsulin resistant (NIR) and insulin resistant (IR), and were weight- and age-matched with healthy girls. Inflammatory cytokines (TNF-α, IL-6, Il-10, TGF-ß) and lipokines (leptin, adiponectin), the reactant hs-CRP, and in vitro inflammatory lympho-monocyte response to microbial stimulus were evaluated. In healthy and PCOS subjects, leptin and hs-CRP were correlated with BMI, whereas adiponectin was significantly reduced in all PCOS groups. Although cytokines were similar in all groups, Interleukin-6 (IL-6) was significantly higher in IR PCOS. Moreover, in the latter group lipopolysaccharide-activated monocytes secreted significantly higher levels of IL-6 compared to NIR and control subjects. To conclude, IR PCOS displayed increased IL-6 serum levels and higher secretion in LPS-activated monocytes, whilst revealing no differences for other inflammatory cytokines. These results suggest that in PCOS patients an altered immune response to inflammatory stimuli is present in IR, likely contributing towards determining onset of a low grade inflammation.

Endocannabinoids may mediate the ability of (n-3) fatty acids to reduce ectopic fat and inflammatory mediators in obese Zucker rats.

Dietary (n-3) long-chain PUFA [(n-3) LCPUFA] ameliorate several metabolic risk factors for cardiovascular diseases, although the mechanisms of these beneficial effects are not fully understood. In this study, we compared the effects of dietary (n-3) LCPUFA, in the form of either fish oil (FO) or krill oil (KO) balanced for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content, with a control (C) diet containing no EPA and DHA and similar contents of oleic, linoleic, and alpha-linolenic acids, on ectopic fat and inflammation in Zucker rats, a model of obesity and related metabolic dysfunction. Diets were fed for 4 wk. Given the emerging evidence for an association between elevated endocannabinoid concentrations and metabolic syndrome, we also measured tissue endocannabinoid concentrations. In (n-3) LCPUFA-supplemented rats, liver triglycerides and the peritoneal macrophage response to an inflammatory stimulus were significantly lower than in rats fed the control diet, and heart triglycerides were lower, but only in KO-fed rats. These effects were associated with a lower concentration of the endocannabinoids, anandamide and 2-arachidonoylglycerol, in the visceral adipose tissue and of anandamide in the liver and heart, which, in turn, was associated with lower levels of arachidonic acid in membrane phospholipids, but not with higher activity of endocannabinoid-degrading enzymes. Our data suggest that the beneficial effects of a diet enriched with (n-3) LCPUFA are the result of changes in membrane fatty acid composition. The reduction of substrates for inflammatory molecules and endocannabinoids may account for the dampened inflammatory response and the physiological reequilibration of body fat deposition in obese rats.

Antimicrobial sulfonamides clear latent Kaposi sarcoma herpesvirus infection and impair MDM2-p53 complex formation.

Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8, is the causative agent of Kaposi sarcoma; this malignant angiosarcoma is usually treated with conventional antitumor agents that can control disease evolution, but do not clear the latent KSHV episome that binds to cellular DNA. Some commercial antibacterial sulfonamides were tested for the ability to suppress latent KSHV. Quantitative PCR (qPCR) and cytofluorometry assays were used for detecting both viral DNA and the latency factor LANA (latency-associated nuclear antigen) in BC3 cells, respectively. The capacity of sulfonamides to impair MDM2-p53 complex formation was detected by an enzyme-linked immunosorbent assay method. The analysis of variance was performed according to one-way analysis of variance with Fisher as a post hoc test. Here we show that sulfonamide antibiotics are able to suppress the KSHV latent state in permanently infected BC3 lymphoma cells and interfere with the formation of the MDM2-p53 complex that KSHV seemingly needs to support latency and to trigger tumor cell transformation. These findings detected a new molecular target for the activity of sulfonamides and offer a new potential perspective for treating KSHV-induced lymphoproliferative diseases.

Multidrug resistance P-glycoprotein dampens SR-BI cholesteryl ester uptake from high density lipoproteins in human leukemia cells.

Tumor cells are characterised by a high content of cholesterol esters (CEs), while tumor-bearing patients show low levels of high-density lipoproteins (HDLs). The origin and significance of high CE levels in cancer cell biology has not been completely clarified. Recent evidence that lymphoblastic cells selectively acquire exogenous CE from HDL via the scavenger receptor SR-BI has drawn attention to the additional membrane proteins involved in this pathway. P-glycopotein-MDR1 (P-gp) is a product of the MDR1 gene and confers resistance to antitumor drugs. Its possible role in plasma membrane cholesterol trafficking and CE metabolism has been suggested. In the present study this aspect was investigated in a lymphoblastic cell line selected for MDR1 resistance. CEM were made resistant by stepwise exposure to low (LR) and high (HR) doses of vincristine (VCR). P-gp activity ((3)H-vinblastine), CE content, CE and triglycerides (TG) synthesis ((14)C-oleate), neutral lipids and Dil-HDL uptake (fluorescence), SR-BI, ABCA1 and P-gp protein expression (western blotting) were determined. To better evaluate the relationship between CE metabolism and P-gp activity, the ACAT inhibitor Sandoz-58035 and the P-gp inhibitors progesterone, cyclosporine and verapamil were used. CE content and synthesis were similar in the parental and resistant cells. However, in the latter population, SR-BI protein expression increased, whereas CE-HDL uptake decreased. These changes correlated with the degree of VCR-resistance. As well as reverting MDR1-resistance, the inhibitors of P-gp activity induced the CE-HDL/SR-BI pathway by reactivating membrane cholesterol trafficking. Indeed, CE-HDL uptake, SRBI expression and CE content increased, whereas there was a decrease in cholesterol esterification. These results demonstrated that P-gp overexpression impairs anticancer drug uptake as well as the SR-BI mediated selective CE-HDL uptake. This suggests that these membrane proteins act in an opposite manner on the same transport mechanism. Therefore, the dampening activity of P-gp in this pathway and its reversal by P-gp inhibitors open new strategies for antitumor therapy in drug-resistant tumors.

High-density lipoprotein contribute to G0-G1/S transition in Swiss NIH/3T3 fibroblasts.

High density lipoproteins (HDLs) play a crucial role in removing excess cholesterol from peripheral tissues. Although their concentration is lower during conditions of high cell growth rate (cancer and infections), their involvement during cell proliferation is not known. To this aim, we investigated the replicative cycles in synchronised Swiss 3T3 fibroblasts in different experimental conditions: i) contact-inhibited fibroblasts re-entering cell cycle after dilution; ii) scratch-wound assay; iii) serum-deprived cells induced to re-enter G1 by FCS, HDL or PDGF. Analyses were performed during each cell cycle up to quiescence. Cholesterol synthesis increased remarkably during the replicative cycles, decreasing only after cells reached confluence. In contrast, cholesteryl ester (CE) synthesis and content were high at 24 h after dilution and then decreased steeply in the successive cycles. Flow cytometry analysis of DiO-HDL, as well as radiolabeled HDL pulse, demonstrated a significant uptake of CE-HDL in 24 h. DiI-HDL uptake, lipid droplets (LDs) and SR-BI immunostaining and expression followed the same trend. Addition of HDL or PDGF partially restore the proliferation rate and significantly increase SR-BI and pAKT expression in serum-deprived cells. In conclusion, cell transition from G0 to G1/S requires CE-HDL uptake, leading to CE-HDL/SR-BI pathway activation and CEs increase into LDs.

Abnormal macrophage response to microbial stimulus in a 43-year-old man with a severe form of atherosclerosis: a case report.

INTRODUCTION: New evidence indicates infections are emerging as risk factors for atherosclerosis although their specific role in the development and progression of atherosclerosis is still unclear. CASE PRESENTATION: A 43-year-old Caucasian man who had been treated for four years for multiple sclerosis progressively manifested systemic hypertension, polycythemia, peripheral arterial occlusion with intermittent claudication, and persistent headaches. In 2006, an instrumental analysis (magnetic resonance imaging) of our patient revealed widespread fibrocalcific atherosclerotic lesions which accounted for all his current symptoms, including those related to microbial stimulus. Two particular aspects were of interest, namely a lack of conventional cardiovascular risk factors and a negative family history for cardiovascular events. His chemical blood tests all yielded negative findings although a low positive hepatitis C virus-ribonucleic acid titer was detected. The titer had progressively increased and worsening atherosclerosis threatened the life of our patient. Interferon therapy was not appropriate for our patient due to the severe adverse effects observed shortly after its administration. CONCLUSIONS: The reaction of individual cells to infections may provide an explanation as to why individuals with a similar microbial burden, corrected for the presence of other risk factors, display a different susceptibility to developing or worsening atherosclerosis. The identification of susceptible individuals and the treatment even of silent infections may provide an additional tool against atherosclerosis and its clinical complications. The evaluation of cell susceptibility before and after the correction of risk factors may contribute to the assessment of the efficacy of drug therapy.

Lipid droplet changes in proliferating and quiescent 3T3 fibroblasts.

Lipid droplets (LDs) are fat-storing organelles present in virtually all eukaryotic cells and involved in many aspects of cell biology related to lipid metabolism and cholesterol homeostasis. In this study, we investigated the presence of LDs in proliferating and quiescent (contact-inhibited) 3T3 fibroblasts to verify a correlation with cell growth. LDs were characterized by Nile red staining, positivity to adipophilin and negativity to perilipin. LDs were numerous in proliferating cells, but very few in quiescent cells. However, the fraction of quiescent cells, which resumed proliferation after scratch-wound assay, also resumed the formation of LDs. In proliferating cells, the number of LDs correlated with the DNA content, suggesting a continuous accumulation of LDs during cell growth. These findings were supported by biochemical data showing much higher rates of cholesterol esterification and triglyceride synthesis in proliferating cells. Both filipin staining and the fluorescent cholesterol analog dehydroergosterol revealed the presence of an intense traffic of free cholesterol, mediated by acidic vesicles, in proliferating cells. Nile red ratiometric measurements revealed a different lipid composition of LDs in proliferating and quiescent cells. Changes in the number and composition of LDs were also found in growing cells treated with inhibitors of cholesterol esterification (Sandoz 58-035), endosomal cholesterol efflux (U18666A) and V-ATPase (bafilomycin-A1).

Production of inflammatory molecules in peripheral blood mononuclear cells from severely glucose-6-phosphate dehydrogenase-deficient subjects.

OBJECTIVE: We have previously demonstrated that Mediterranean glucose-6-phosphate dehydrogenase (G6PD)-deficient peripheral blood mononuclear cells (PBMC) respond to mitogenic stimuli with a reduced cholesterol synthesis and growth. In the present study, we have investigated the release of inflammatory molecules by PBMC following a mitogenic stimulus, as well as the transformation to foam cells of monocyte-derived macrophages from severely G6PD-deficient and normal subjects. METHODS AND RESULTS: PBMC from G6PD-deficient subjects produced interleukin (IL)-1beta and IL-6 to a lower extent compared with normal subjects. 5-Hydroxyeicosatetraenoic acid, a primary product of 5-lipoxygenase, was slightly decreased. Tumour necrosis factor-alpha and IL-1beta secretion was significantly reduced in monocyte-derived macrophages. No difference was found in IL-10 secretion, whereas transforming growth factor-beta was invariably found to be significantly higher in G6PD-deficient cells. In cells incubated with acetylated low-density lipoprotein, cholesterol esterification and its storage in lipid droplets were lower than in normal G6PD cells. CONCLUSIONS: We conclude that by reducing the secretion of inflammatory molecules by PBMC and increasing the secretion of transforming growth factor-beta and the capability of monocyte-derived macrophages to accumulate lipid droplets and convert into foam cells, G6PD deficiency may confer a partial protection against atherosclerosis leading to the reduced risk of cardiovascular diseases reported in G6PD-deficient subjects.