Subjects with familial hypercholesterolemia are characterized by an inflammatory phenotype despite long-term intensive cholesterol lowering treatment.

OBJECTIVE: The atherosclerotic process is driven by elevated Low-density lipoprotein (LDL)-cholesterol in combination with enhanced inflammatory responses. Several mediators participate in this complex inflammatory network including members of the tumour necrosis factor (receptor) superfamily. Familial hypercholesterolemia (FH) is associated with increased risk of developing premature atherosclerosis. Statin treatment may normalize LDL-cholesterol levels, but it is not known if the inflammatory responses are normalized in statin-treated FH patients. METHODS: In long-term statin-treated FH subjects (n=33) and healthy controls (n=10) the expression of tumour necrosis factor (receptor) superfamily related genes in peripheral blood mononuclear cells (PBMC) were analyzed by real-time quantitative RT-PCR. TNFα release was measured in PBMC from patients and controls by immunoassay. RESULTS: In FH patients with normal LDL-cholesterol, after a median of 17 years of statin treatment, our major findings were: (i) Gene expression of CD137, LIGHT (lymphotoxins inducible expression, competes with HSV glycoprotein D for HVEM, a receptor expressed on T-lymphocytes), HVEM (Herpesvirus entry mediator), the two TNFα Receptors (TNFR1 and TNFR2), TNF related apoptosis inducing ligand (TRAIL) and CD40 were increased in PBMC from FH patients compared to controls. (ii) The release of TNFα in PBMC from FH patients, in response to LPS was increased compared to controls. (iii) PBMC from FH patients had enhanced spontaneous release of TNFα when incubated in the presence of control serum and in particular in the presence of FH serum. CONCLUSION: Despite long-term statin therapy, an increased expression of several TNF related genes in PBMC isolated from FH patients was observed. Our findings may implicate a pathogenic role for inflammation and TNF related molecules in FH, and these findings suggest the possibility that novel treatment modalities beyond that of statins and lipid lowering drugs may be useful in FH subjects.

Low level of inflammatory marker in hyperhomocysteinemic patients on statin therapy.

Inflammatory processes including increased activation of chemokines play an important role in atherogenesis. Patients with hyperhomocysteinemia have increased risk for cardiovascular events that potentially involve enhanced inflammation. Statins may have anti-inflammatory actions at least partly independent on their lipid-lowering effects. In the present study we examined the association between statins and chemokine levels in patients with hyperhomocysteinemia. Our major findings were (i) patients with hyperhomocysteinemia on statin treatment (n = 14) have significantly lower plasma levels of the CXC chemokine epithelial neutrophil activating peptide (ENA)-78 compared to hyperhomocysteinemic patients not on statin treatment (n = 8). In fact, levels of ENA-78 in statin-treated patients did not differ from those of healthy controls (n = 17); (ii) plasma levels of ENA-78 and growth-related oncogene (GRO)α correlated with levels of LDL-cholesterol and homocysteine; (iii) in contrast, plasma levels of the CC chemokine monocyte chemoattractant peptide (MCP)-1 were similar between statin-users, non-statin users and controls, and did not correlate with levels of LDL-cholesterol or homocysteine; and (iv) in vitro studies showed that simvastatin significantly reduced release of ENA-78, GROα and MCP-1 from peripheral blood mononuclear cells in healthy controls (n = 7) in a concentration-dependent manner, without affecting release of RANTES. Our data may suggest that ENA-78 and GROα may be involved in the inflammatory arm of atherogenesis in patients with elevated risk of cardiovascular disease, with potential down-regulatory effect of statins.

Subjects with low plasma HDL cholesterol levels are characterized by an inflammatory and oxidative phenotype.

BACKGROUND: Epidemiological studies have shown that low plasma levels of high-density lipoprotein (HDL) cholesterol are associated with increased risk of cardiovascular disease, but the mechanisms for the possible atheroprotective effects of HDL cholesterol have still not been fully clarified, in particular in relation to clinical studies. OBJECTIVE: To examine the inflammatory, anti-oxidative and metabolic phenotype of subjects with low plasma HDL cholesterol levels. METHODS AND RESULTS: Fifteen subjects with low HDL cholesterol levels (eleven males and four females) and 19 subjects with high HDL (three males and 16 females) were recruited. Low HDL cholesterol was defined as ≤10th age/sex specific percentile and high HDL-C was defined as ≥90 age/sex specific percentile. Inflammatory markers in circulation and PBMC gene expression of cholesterol efflux mediators were measured. Our main findings were: (i) subjects with low plasma HDL cholesterol levels were characterized by increased plasma levels of CRP, MMP-9, neopterin, CXCL16 and ICAM-1 as well as low plasma levels of adiponectin, suggesting an inflammatory phenotype; (ii) these individuals also had reduced paraoxonase (PON)1 activity in plasma and PON2 gene expression in peripheral blood mononuclear cells (PBMC) accompanied by increased plasma levels of oxidized LDL suggesting decreased anti-oxidative capacity; and (iii) PBMC from low HDL subjects also had decreased mRNA levels of ABCA1 and ABCG1, suggesting impaired reverse cholesterol transport. CONCLUSION: Subjects with low plasma HDL cholesterol levels are characterized by an inflammatory and oxidative phenotype that could contribute to the increased risk of atherosclerotic disorders in these subjects with low HDL levels.

Cholesterol efflux mediators in homozygous familial hypercholesterolemia patients on low-density lipoprotein apheresis.

BACKGROUND: Homozygous familial hypercholesterolemia (FH) is a rare disorder that may affect 1 person per million. Early initiation of aggressive cholesterol-lowering therapy is essential to prevent premature coronary heart disease. Selective removal of low-density lipoprotein (LDL) by LDL apheresis is a reliable method of treatment. METHODS AND RESULTS: Cholesterol efflux mediators of homozygous FH patients on weekly LDL apheresis were compared with those of age- and sex-matched heterozygous FH patients receiving oral medication only and with healthy control subjects. The data show that (1) compared with healthy controls, homozygous FH patients have significantly lower plasma levels of high-density lipoprotein cholesterol and apoA-I and significantly lower cholesterol-acceptor capacity of serum to promote cholesterol efflux from cholesterol-loaded THP-1 cells, combined with significantly lower peripheral blood mononuclear cell gene expression levels of ATP-binding cassette (ABC) transporter G1 and borderline-significantly lower levels of ABCA1 and scavenger receptor class B type I (SR-BI); and (2) compared with pre-LDL apheresis (a day before treatment), postapheresis (15 days later; on the day after the weekly treatment) levels of HDL cholesterol and apoA-I were significantly reduced, with no significant effect on cholesterol-acceptor capacity of serum or on peripheral blood mononuclear cell gene expression levels of the cellular transporters, except for a borderline-significant reduction in ABCA1 mRNA levels. CONCLUSIONS: The data showing decreased levels of cholesterol efflux mediators in plasma and cells may suggest that the overall cholesterol efflux capacity is impaired in homozygous FH patients. However, LDL apheresis may maintain cholesterol efflux capacity, despite a lowering levels of high-density lipoprotein cholesterol and apoA-I.

Elevated serum MMP-9/TIMP-1 ratio in patients with homozygous familial hypercholesterolemia: effects of LDL-apheresis.

OBJECTIVE: Matrix degradation within an atherosclerotic plaque is an important pathogenic factor in atherosclerosis, and is largely modulated by the balance between matrix metalloproteinases (MMPs) and their endogenous inhibitors (i.e., tissue inhibitor of MMPs [TIMPs]). Familial hypercholesterolemia (FH) is a rare inherited disorder associated with premature coronary heart disease. The aim of the present study was to examine MMP-9 and TIMP-1 on plasma and cellular mRNA levels in homozygous FH patients (n=7) compared with age- and sex-matched heterozygous FH patients (n=6), and with healthy subjects (n=7), and to test whether once-weekly LDL-apheresis (three consecutive sessions) of homozygous FH patients show short-term effects on these variables. RESULTS: The main findings were that (i) Compared to healthy control subjects, homozygous FH patients have significantly higher serum levels of MMP-9 and lower levels of TIMP-1, and consequently significantly higher MMP-9/TIMP-1 ratio, potentially reflecting higher MMP-9 activity. (ii) Peripheral blood mononuclear cells (PBMC) isolated from FH homozygotes have significantly higher mRNA levels of MMP-9 compared to cells from heterozygotes. (iii) TNFα-stimulated PBMC from FH homozygotes released borderline-significantly more MMP-9 than cells from heterozygotes and healthy controls. (iv) LDL-apheresis (one day before treatment versus fifteen days later, on the day after the weekly treatment) had no significant short-term effect on any of the MMP-9 and TIMP-1 variables measured in serum and cells. CONCLUSIONS: The data may suggest that homozygous FH patients have an enhanced matrix degrading potential as compared with heterozygous FH patients and healthy controls, potentially contributing to the increased cardiovascular risk observed in these patients.

Maternal familial hypercholesterolaemia (FH) confers altered haemostatic profile in offspring with and without FH.

INTRODUCTION: Patients with familial hypercholesterolaemia (FH) are characterized by high total and LDL cholesterol. Pregnant women with FH have higher absolute levels of total and LDL cholesterol, and a more pro-coagulant pattern compared with healthy pregnant women. Maternal hypercholesterolaemia has been shown to affect early atherosclerosis formation in the offspring. The aim of the present study was to investigate whether maternal FH leads to differences in plasma or serum levels of haemostatic and fibrinolytic markers in children with and without FH born of mothers with FH compared to control children born of non-FH mothers. METHODS AND RESULTS: Children with (n=9) and without (n=7) FH born of mothers with FH, as well as control children (n=16) born of non-FH mothers were included in the study. The concentrations of tissue plasminogen activator, plasminogen activator inhibitor (PAI-1), tissue factor (TF), TF pathway inhibitor (TFPI), thrombomodulin, fibrinogen, prothrombin fragment 1+2 and von Willebrand Factor were measured. Our findings show i) higher levels of PAI-1 and TFPI in children with and without FH born of mothers with FH compared with control children, ii) lower levels of thrombomodulin in children with FH compared with control children, and iii) significant correlations between maternal PAI-1 levels during pregnancy and PAI-1 levels in the offspring. CONCLUSIONS: We found that maternal FH may confer an unfavourable phenotype by affecting haemostatic and fibrinolytic markers in offspring independent of the children's FH status. However, the association between maternal hypercholesterolaemia and haemostatic risk markers in the offspring needs to be further elucidated.

Apheresis in homozygous familial hypercholesterolemia: the results of a follow-up of all Norwegian patients with homozygous familial hypercholesterolemia.

BACKGROUND: Homozygous familial hypercholesterolemia (HoFH), which affects 1 in a million individuals, leads to extremely elevated levels of cholesterol and early-onset cardiovascular disease. OBJECTIVE: The aim of this study was to assess all 7 HoFH patients treated with low-density lipoprotein (LDL) apheresis in Norway with respect to quality of life, clinical and laboratory assessments, and cardiovascular status. METHODS: Apheresis treatment and assessment of cardiovascular status was performed at local hospitals but coordinated by the Lipid Clinic that has followed all patients since diagnosis. Quality of life was evaluated by a validated questionnaire. RESULTS: Results are shown as median (min-max). LDL cholesterol at diagnosis (untreated) was 704 (592-1268) mg/dL (18.2 [15.3-32.8] mmol/L). Medication was initiated at age 9 (2-35) years, and apheresis treatment at age 10 (6-44) years. Regular once-weekly apheresis combined with the maximum-tolerable doses of a statin and ezetimibe reduced LDL cholesterol to 197 (170-282) mg/dL (5.1 [4.5-7.3] mmol/L) pre-apheresis and 85 (50-108) mg/dL (2.2 [1.3-2.8] mmol/L) post-apheresis. Calculated interval mean LDL cholesterol was 162 (135-220) mg/dL (4.2 [3.5-5.7] mmol/L). Duration of apheresis treatment was 11 (1-24) years. Cardiovascular manifestations progressed in most patients despite the apheresis treatment. The subjects' quality of life was comparable with that of a healthy population, with the exception of two patients, who were significantly affected by coronary disease. CONCLUSIONS: Well-tolerated, once-weekly LDL apheresis achieves lower interval mean LDL cholesterol levels between apheresis treatments than previously reported for apheresis every second week. However, progressions of cardiovascular manifestations still occurred, which highlights the importance of earlier and even more aggressive treatment and follow-up in HoFH.

Lipoprotein(a) levels in coronary heart disease-susceptible and -resistant patients with familial hypercholesterolemia.

OBJECTIVE: Familial hypercholesterolemia (FH) is caused by defects in genes coding for proteins involved in low density lipoprotein (LDL) metabolism, and is associated with increased risk of premature coronary heart disease (CHD). The clinical phenotype of FH exhibits marked variability due to additional metabolic and environmental factors, and further biomarkers are required for appropriate risk assessment. The aim of the present study was to search for risk markers among FH patients. METHODS AND RESULTS: Clinical and biochemical parameters of FH subjects with early CHD events (CHD-susceptible) and FH subjects with late or no CHD events (CHD-resistant) were compared. Our data show that CHD-susceptible FH patients had significantly higher Lipoprotein (Lp) (a) levels compared to CHD-resistant FH patients. When subdividing by gender, the main findings were that (i) CHD-susceptible women had significantly higher levels of both Lp(a), low density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B as compared to CHD-resistant women, and (ii) CHD-resistant women had significantly lower Lp(a) levels and higher high density lipoprotein (HDL) cholesterol and apoA-I levels compared to CHD-resistant men. CONCLUSIONS: The data suggest that Lp(a) may be an important coronary risk marker in FH patients, in particular in combination with elevated LDL cholesterol levels among female subjects. Thus, measurement of Lp(a) levels may help identifying high-risk individuals who could benefit from an aggressive therapy, including statins to reduce LDL-cholesterol to guideline-recommended levels.

Children with familial hypercholesterolemia are characterized by an inflammatory imbalance between the tumor necrosis factor α system and interleukin-10.

OBJECTIVE: Familial hypercholesterolemia (FH) is associated with increased risk of premature atherosclerosis. Increasing evidence supports involvement of inflammation in atherogenesis. The inflammatory cytokine tumor necrosis factor (TNF)α has been regarded as a key mediator in the development of atherosclerosis due to its involvement in several stages in this process. We hypothesized that children with FH, as a model of early atherosclerosis, have different serum levels of inflammation markers than healthy control children. METHODS: We measured serum levels of TNFα, as well as its endogenous inhibitors (i.e., soluble TNF receptors [sTNFR] 1 and 2) and the anti-inflammatory cytokine interleukin (IL)-10 in healthy children (7-20 years) with (n=102) and without (n=48) heterozygote FH as well as adult FH subjects (n=20) and healthy adult controls (n=16). RESULTS: The main findings were: Compared to control children, FH children had higher serum levels of TNFα, accompanied by lower sTNFRs levels, resulting in an increased TNFα/sTNFRs ratio (P<0.05), potentially reflecting enhanced TNFα activity. In contrast to the increased TNFα levels, FH children had decreased serum levels of IL-10 (P<0.01) resulting in an increased TNFα/IL-10 ratio (P<0.01). We did not observe any difference in the same parameters between adult subjects with and without FH. CONCLUSIONS: FH children are characterized by an inflammatory imbalance between TNFα and IL-10, potentially contributing to the accelerated atherosclerotic process in these individuals.

Suggestive evidence of associations between liver X receptor ß polymorphisms with type 2 diabetes mellitus and obesity in three cohort studies: HUNT2 (Norway), MONICA (France) and HELENA (Europe).

BACKGROUND: The liver X receptors (LXR) α and ß regulate lipid and carbohydrate homeostasis and inflammation. Lxrß⁻/⁻ mice are glucose intolerant and at the same time lean. We aimed to assess the associations between single nucleotide polymorphisms (SNPs) in LXRß and risk of type 2 diabetes mellitus (T2DM), obesity and related traits in 3 separate cohort studies. METHODS: Twenty LXRß SNPs were identified by sequencing and genotyped in the HUNT2 adult nested case-control study for T2DM (n = 835 cases/1986 controls). Five tag-SNPs (rs17373080, rs2695121, rs56151148, rs2303044 and rs3219281), covering 99.3% of the entire common genetic variability of the LXRß gene were identified and genotyped in the French MONICA adult study (n = 2318) and the European adolescent HELENA cross-sectional study (n = 1144). In silico and in vitro functionality studies were performed. RESULTS: We identified suggestive or significant associations between rs17373080 and the risk of (i) T2DM in HUNT2 (OR = 0.82, p = 0.03), (ii) obesity in MONICA (OR = 1.26, p = 0.05) and (iii) overweight/obesity in HELENA (OR = 1.59, p = 0.002). An intron 4 SNP (rs28514894, a perfect proxy for rs17373080) could potentially create binding sites for hepatic nuclear factor 4 alpha (HNF4α) and nuclear factor 1 (NF1). The C allele of rs28514894 was associated with ~1.25-fold higher human LXRß basal promoter activity in vitro. However, no differences between alleles in terms of DNA binding and reporter gene transactivation by HNF4α or NF1 were observed. CONCLUSIONS: Our results suggest that rs17373080 in LXRß is associated with T2DM and obesity, maybe via altered LXRß expression.

Cystatin C levels in plasma and peripheral blood mononuclear cells among hyperhomocysteinaemic subjects: effect of treatment with B-vitamins.

Homocysteine has been related to increased risk of CVD. Matrix degradation and inflammation may be involved in this link between hyperhomocysteinaemia and CVD. Recent studies suggest that cystatin C can modulate matrix degradation and inflammation. The present study measured cystatin C at protein (plasma) and mRNA levels (peripheral blood mononuclear cells (PBMC)) in hyperhomocysteinaemic individuals (n 37, female seven and male thirty, aged 20-70 years) before and after B-vitamin supplementation for 3 months in a randomised, placebo-controlled double-blind trial. In a cross-sectional study, seventeen of the hyperhomocysteinaemic subjects were age- and sex-matched to healthy controls (n 17). Our main findings were: (i) as compared with controls, hyperhomocysteinaemic subjects tended to have higher plasma concentrations of cystatin C and lower mRNA levels of cystatin C in PBMC; (ii) compared with placebo, treatment of hyperhomocysteinaemic individuals with B-vitamins significantly increased plasma levels of cystatin C and mRNA levels of cystatin C in PBMC; (iii) while plasma levels of cystatin C were positively correlated with plasma levels of TNF receptor-1, mRNA levels of cystatin C in PBMC were inversely correlated with this TNF parameter. Taken together, our findings suggest that disturbed cystatin C levels may be a characteristic of hyperhomocysteinaemic individuals, potentially related to low-grade systemic inflammation in hyperhomocysteinaemic subjects, and that B-vitamins may modulate cystatin C levels in these individuals.

Dysregulated RANK ligand/RANK axis in hyperhomocysteinemic subjects: effect of treatment with B-vitamins.

BACKGROUND AND PURPOSE: Homocysteine has been linked to increased risk of ischemic stroke and other cardiovascular events. Matrix degradation and inflammation play an important role in these disorders, and we have demonstrated increased levels of matrix-degrading enzymes and inflammatory cytokines in hyperhomocysteinemic individuals. Recent studies suggest that RANK ligand (RANKL) through interaction with its receptor RANK can modulate matrix degradation and inflammation. The present study aimed to examine the role of the RANKL/RANK axis in hyperhomocystinemia. METHODS: RANKL/RANK was measured on protein or mRNA level before and after B-vitamin supplementation in hyperhomocysteinemic individuals. We also examined the in vitro effects of soluble RANKL in peripheral blood mononuclear cells from hyperhomocysteinemic individuals. RESULTS: Our main findings were: (1) compared to peripheral blood mononuclear cells from controls, cells from hyperhomocysteinemic individuals had significantly higher gene expression of RANKL and RANK; (2) folic acid treatment for 6 weeks in an open, uncontrolled study significantly reduced gene expression of RANKL/RANK in peripheral blood mononuclear cells from these individuals; (3) compared to placebo, treatment with folic acid, vitamin B(12), and vitamin B(6) for 3 months in a randomized, double-blind trial significantly lowered serum levels of soluble RANKL in hyperhomocysteinemic individuals; and (4) in vitro, soluble RANKL markedly increased the release of matrix metalloproteinase-9 and inflammatory cytokines from peripheral blood mononuclear cells in hyperhomocysteinemic subjects. CONCLUSIONS: Our findings suggest a dysregulated RANKL/RANK axis in hyperhomocysteinemic subjects. Based on their role in atherogenesis, this enhanced expression of RANKL and RANK could contribute to the increased risk of cardiovascular disease in hyperhomocystinemia. Moreover, treatment with B-vitamins may have beneficial implications for plaque stability in these individuals.

The antiatherogenic function of HDL is impaired in hyperhomocysteinemic subjects.

High plasma homocysteine concentrations have been associated with increased risk of cardiovascular disease, whereas plasma HDL concentration is inversely correlated to such disorders. We hypothesized that hyperhomocysteinemic subjects may have dysfunctional HDL. We therefore investigated the ability of serum from hyperhomocysteinemic male and female subjects (n = 10) and control subjects (n = 10) to induce cholesterol efflux and to inhibit release of inflammatory mediators from human umbilical vein endothelial cell. We found that serum from hyperhomocysteinemic subjects had impaired ability to induce cholesterol efflux from lipid-loaded macrophages compared with healthy controls. HDL from those with markedly raised homocysteine concentrations had a reduced antiinflammatory effect in tumor necrosis factor-alpha-activated endothelial cells with an attenuated suppressive effect on interleukin-6 growth-related oncogene-alpha release. Also, the activity of paraoxonase in serum, a multifunctional enzyme with antioxidative effects in relation to the function of HDL, was significantly reduced in hyperhomocysteinemic subjects, in particular those with markedly raised homocysteine concentration. Our findings suggest that hyperhomocysteinemic individuals have dysfunctional HDL particles with attenuated antiatherogenic activity and may represent a novel explanation for the increased risk of cardiovascular events in these individuals.

Impaired inhibitory effect of interleukin-10 on the balance between matrix metalloproteinase-9 and its inhibitor in mononuclear cells from hyperhomocysteinemic subjects.

BACKGROUND AND PURPOSE: Homocysteine has been linked to increased risk of ischemic stroke and other cardiovascular events, but the mechanism by which elevated plasma levels of homocysteine promotes atherogenesis remains unclear. Matrix degradation, partly regulated by the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs), plays an important role in atherogenesis and plaque destabilization, and we hypothesized an imbalance between MMPs and TIMPs in hyperhomocysteinemia. METHODS: Serum MMP-9 and TIMP-1 was measured in 12 hyperhomocysteinemic and 12 control subjects. The release of MMP-9 and TIMP-1, with and without interleukin-10 (IL-10), and the effect of IL-10 on signal transducer and activator of transcription 3 (STAT3) phosphorylation were measured in peripheral blood mononuclear cells (PBMCs) from hyperhomocysteinemic and control subjects. RESULTS: Our main findings were: (1) hyperhomocysteinemic subjects had raised serum levels of MMP-9 and MMP-9/TIMP-1 ratio comparing healthy controls; (2) although IL-10 markedly suppressed MMP-9 release from PBMCs in controls, no or only minor effect was seen in hyperhomocysteinemic subjects; (3) although IL-10 enhanced TIMP-1 levels in PBMCs from both hyperhomocysteinemic and control subjects, the increase was more prominent in controls, resulting in a marked difference in IL-10-induced changes in MMP-9/TIMP-1 ratio between these 2 groups; and (4) comparing PBMCs from controls, cells from hyperhomocysteinemic individuals had impaired IL-10-induced STAT3 phosphorylation. CONCLUSIONS: Our findings suggest an attenuated inhibitory response to IL-10 on MMP-9 activity in hyperhomocysteinemic subjects, potentially promoting atherogenesis and plaque instability, representing a novel explanation for increased risk for atherosclerotic disease in these individuals.

Triglyceride-rich HDL3 from patients with familial hypercholesterolemia are less able to inhibit cytokine release or to promote cholesterol efflux.

Familial hypercholesterolemia (FH) is associated with heterogeneity of the onset and severity of coronary heart disease (CHD). In this study, we investigated different low-grade proinflammatory markers and the atheroprotective function of the HDL3 subfraction in FH-patients (n = 13) with identical LDL-receptor mutations and in age- and sex-matched healthy controls (n = 11). Compared with healthy controls, FH-patients had greater gene expressions of the proatherogenic mediators TNF-alpha and IL-8 in circulating peripheral blood mononuclear cells. In addition, they had a higher serum concentration of intercellular adhesion molecule-1 (ICAM-1) and a lower net antioxidant capacity. FH-derived HDL3 with a high level of triglycerides had a reduced capacity to inhibit the release of IL-8 from TNF-alpha-stimulated human umbilical vein endothelial cells (HUVEC) [1.864 mg/L (1.461-2.208 mg/L) vs. 1.466 mg/L (1.225-1.643 mg/L); P < 0.05; median (range)], and a reduced capacity to promote cholesterol efflux from lipid-loaded macrophages [12% (12-14%) vs. 15% (14-18%); P < 0.05; median (range)] compared with HDL3 with a lower triglyceride content. Notably, the degree of inhibition of IL-8 release from HUVEC by HDL3 was correlated with the ability of HDL3 to promote cholesterol efflux (r = -0.80, P = 0.03). In conclusion, compared with healthy controls, FH-patients are characterized by higher levels of low-grade proinflammatory markers, and FH-derived HDL3 with high triglyceride content may be more proatherogenic. These triglyceride rich-HDL3 might be partly responsible for the phenotypic variation among FH-patients with identical LDL-receptor mutations.

Chemokines in children with heterozygous familiar hypercholesterolemia: selective upregulation of RANTES.

OBJECTIVE: Increasing data support the involvement of chemokines in atherogenesis. However, although several studies have shown increased chemokine levels in adult patients, the literature is virtually devoid of data on chemokines in children with hypercholesterolemia. METHODS AND RESULTS: We examined the gene expression of chemokines in peripheral blood mononuclear cells (PBMCs) from clinically healthy children with and without heterozygous familial hypercholesterolemia (FH). Our main findings were: (1) compared with healthy controls, PBMCs from FH children showed significantly higher mRNA levels of RANTES, but not of the other examined chemokines; (2) an opposite pattern was seen in adult FH subjects, with markedly enhanced expression of macrophage inflammatory peptide-1alpha, but not of RANTES; (3) this increased gene expression of RANTES in PBMCs from FH children seemed to reflect enhanced RANTES expression in monocytes but not in T cells; (4) FH children also had raised serum levels of neopterin, additionally suggesting monocyte/macrophage activation in these children; and (5) PBMCs from both FH children and controls showed enhanced release of interleukin 8 on RANTES stimulation in vitro. CONCLUSIONS: Our findings support a role of inflammation also in the early stages of atherogenesis possibly involving monocyte-derived RANTES as an important mediator.

Hyperhomocysteinemic subjects have enhanced expression of lectin-like oxidized LDL receptor-1 in mononuclear cells.

An elevated plasma concentration of homocysteine is an independent risk factor for cardiovascular disease. However, the mechanisms are still unclear. Lectin-like oxidized LDL receptor-1 (LOX-1) has ligand specificity for oxidized LDL (oxLDL). We hypothesized that homocysteine's atherogenic effects may involve LOX-1-mediated mechanisms. We examined the effect of folic acid supplementation for 6 wk and 12 mo (5 mg/d for 1 wk, 1 mg/d for 37 wk and 0.4 mg/d for the remaining 14 wk) on LOX-1 mRNA levels and on oxLDL-induced release of tumor necrosis factor alpha from peripheral blood mononuclear cells in hyperhomocysteinemic individuals. Compared with healthy controls, hyperhomocysteinemic subjects had elevated mRNA levels of LOX-1 in mononuclear cells (P < 0.001), and their mononuclear cells released more tumor necrosis factor alpha (TNFalpha) upon oxLDL stimulation (P = 0.01). This oxLDL-stimulated release of TNFalpha correlated with LOX-1 expression (r = 0.57, P = 0.026). Folic acid treatment led to a normalization of homocysteine levels accompanied by a reduction in LOX-1 gene expression (P < 0.02) and in oxLDL-stimulated release of TNFalpha (P < 0.05). These novel findings suggest both that homocysteine exerts its atherogenic effect in part by elevating levels of LOX-1, thereby enhancing oxLDL-induced inflammatory responses, and most important, that folic acid supplementation may downregulate these responses.

Patients with familial hypercholesterolaemia show enhanced spontaneous chemokine release from peripheral blood mononuclear cells ex vivo. Dependency of xanthomas/xanthelasms, smoking and gender.

AIMS: Familial hypercholesterolaemia (FH) is associated with increased risk of premature atherosclerosis and coronary artery disease (CAD). However, onset of clinically manifested CAD varies widely among patients with heterozygous FH, and we hypothesized that inflammatory mediators such as chemokines could contribute to atherogenesis in these patients. METHODS AND RESULTS: We compared peripheral blood mononuclear cells (PBMCs) from FH patients with an identical mutation with PBMCs from sex- and age-matched healthy controls with respect to spontaneous and oxidized low density lipoprotein (oxLDL)-stimulated release of chemokines. Our main findings were: (1) PBMCs from FH patients spontaneously released significantly higher levels of macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and interleukin (IL)-8, and had a significantly lower oxLDL-stimulatory ratio for MIP-1alpha and MIP-1beta than cells from healthy controls. (2) Spontaneous release of these chemokines correlated positively and stimulatory ratio correlated negatively with plasma concentrations of total and LDL cholesterol. (3) Among FH patients, release of MIP-1alpha, MIP-1beta and IL-8 from PBMCs varied with the presence of xanthomas/xanthelasms, smoking and gender. (4) In vitro studies showed that FH serum but not control serum was able to induce enhanced spontaneous release of chemokines in PBMCs from both FH patients and control subjects. CONCLUSIONS: Our data may suggest that a pathophysiological consequence of FH is enhanced chemokine responses, which in turn may promote recruitment and activation of leukocytes within the vessel wall, contributing to atherosclerosis as well as to the different phenotypes in these patients with an identical FH mutation.

Folic acid treatment reduces elevated plasma levels of asymmetric dimethylarginine in hyperhomocysteinaemic subjects.

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, has been suggested to be a novel risk factor for endothelial dysfunction. It has previously been reported that hyperhomocysteinaemia may be associated with impaired endothelium-dependent vasodilation and reduced plasma level of NO-derived endproducts (NOx). In the present study, plasma levels of arginine and ADMA were measured in twenty-one healthy control subjects, and in twenty-one hyperhomocysteinaemic subjects before and after 6 weeks and 12 months of folic acid supplementation, and compared with previously measured plasma NOx values in the hyperhomocysteinaemic subjects. Compared with control subjects, hyperhomocysteinaemic subjects had higher plasma levels of arginine and ADMA. More importantly, folic acid therapy significantly reduced plasma levels of arginine and ADMA. Furthermore, plasma levels of arginine and ADMA were positively correlated with plasma homocysteine levels and negatively correlated with plasma folate, as well as negatively correlated with plasma NOx. Our results suggest that ADMA may be a mediator of the atherogenic effects of homocysteine.