Lipoprotein Apheresis for Lipoprotein(a)-Associated Cardiovascular Disease: Prospective 5 Years of Follow-Up and Apolipoprotein(a) Characterization.

OBJECTIVE: Lipoprotein(a)-hyperlipoproteinemia (Lp(a)-HLP) along with progressive cardiovascular disease has been approved as indication for regular lipoprotein apheresis (LA) in Germany since 2008. We aimed to study the long-term preventive effect of LA and to assess hypothetical clinical correlations of apolipoprotein(a) (apo(a)) by analyzing genotypes and phenotypes. APPROACH AND RESULTS: This prospective observational multicenter study included 170 patients with Lp(a)-HLP and progressive cardiovascular disease (48.9 years median age at diagnosis) despite other cardiovascular risk factors, including low-density lipoprotein cholesterol had maximally been treated (mean baseline low-density lipoprotein cholesterol: measured, 2.56 mmol/L [98.9 mg/dL] and corrected, 1.72 mmol/L [66.3 mg/dL]). Patients were prospectively investigated during a 5-year period about annual incidence rates of cardiovascular events. In addition, apo(a) isoforms and polymorphisms at the apo(a) gene (LPA) were characterized. One hundred fifty-four patients (90.6%) completed 5 years of follow-up. Mean Lp(a) concentration before commencing regular LA was 108.1 mg/dL. This was reduced by a single LA treatment by 68.1% on average. Significant decline of the mean annual cardiovascular event rate was observed from 0.58±0.53 2 years before regular LA to 0.11±0.15 thereafter (P<0.0001); 95.3% of patients expressed at least 1 small apo(a) isoform. Small apo(a) isoform (35.2%) carrying phenotypes were not tagged by single-nucleotide polymorphisms rs10455872 or rs3798220. CONCLUSIONS: Results of 5 years of prospective follow-up confirm that LA has a lasting effect on prevention of cardiovascular events in patients with Lp(a)-HLP. Patients clinically selected by progressive cardiovascular disease were characterized by a highly frequent expression of small apo(a) isoforms. Only Lp(a) concentration seemed to comprehensively reflect Lp(a)-associated cardiovascular risk, however.

Lipoprotein apheresis in patients with maximally tolerated lipid-lowering therapy, lipoprotein(a)-hyperlipoproteinemia, and progressive cardiovascular disease: prospective observational multicenter study.

BACKGROUND: Lipoprotein(a) (Lp(a)) hyperlipoproteinemia is a major risk factor for cardiovascular disease, which is not affected by treatment of other cardiovascular risk factors. This study sought to assess the effect of chronic lipoprotein apheresis (LA) on the incidence of cardiovascular events in patients with progressive cardiovascular disease receiving maximally tolerated lipid-lowering treatment. METHODS AND RESULTS: In a prospective observational multicenter study, 170 patients were investigated who commenced LA because of Lp(a)-hyperlipoproteinemia and progressive cardiovascular disease. Patients were characterized regarding plasma lipid status, lipid-lowering drug treatment, and variants at the LPA gene locus. The incidence rates of cardiovascular events 2 years before (y-2 and y-1) and prospectively 2 years during LA treatment (y+1, y+2) were compared. The mean age of patients was 51 years at the first cardiovascular event and 57 years at the first LA. Before LA, mean low-density lipoprotein cholesterol and Lp(a) were 2.56±1.04 mmol·L(-1) (99.0±40.1 mg·dL(-1)) and Lp(a) 3.74±1.63 µmol·L(-1) (104.9±45.7 mg·dL(-1)), respectively. Mean annual rates for major adverse coronary events declined from 0.41 for 2 years before LA to 0.09 for 2 years during LA (P<0.0001). Event rates including all vascular beds declined from 0.61 to 0.16 (P<0.0001). Analysis of single years revealed increasing major adverse coronary event rates from 0.30 to 0.54 (P=0.001) for y-2 to y-1 before LA, decline to 0.14 from y-1 to y+1 (P<0.0001) and to 0.05 from y+1 to y+2 (P=0.014). CONCLUSIONS: In patients with Lp(a)-hyperlipoproteinemia, progressive cardiovascular disease, and maximally tolerated lipid-lowering medication, LA effectively lowered the incidence rate of cardiovascular events. CLINICAL TRIAL REGISTRATION URL: https://drks-neu.uniklinik-freiburg.de. Unique identifier: DRKS00003119.

Sympathetic function in human carriers of melanocortin-4 receptor gene mutations.

CONTEXT: Melanocortinergic pathways clearly appear to be involved in obesity-associated sympathetic overactivity and its hemodynamic and thermoregulatory consequences. Individuals with dysfunctional mutations in the melanocortin-4 receptor gene (MC4R) are subject to obesity without developing hypertension. OBJECTIVE: This study aimed at characterizing the impact of the MC4R on sympathetic nerve traffic relevant to the cardiovascular system in humans. PARTICIPANTS: Participants included eight heterozygous carriers of MC4R mutations leading to a reduced function and control subjects matched for gender, age, and body mass index. MEASUREMENTS: We investigated vasoconstrictive muscle sympathetic nerve activity (MSNA), a direct measure of central sympathetic nervous outflow. MSNA was recorded microneurographically from the peroneal nerve at supine rest and during apnea-induced sympathoexcitation. Sympathetic activity was correlated with serum leptin levels and hemodynamic and anthropometric data. RESULTS: Individuals with MC4R impairment due to functional MC4R mutations were characterized by an inverse correlation between MSNA with body mass index and leptin levels, with the most obese subjects having the lowest MSNA. Resting MSNA, diastolic blood pressure, and heart rate tended to be lower in MC4R mutation carriers, and stimulated MSNA during apnea was significantly lower as compared with control subjects. CONCLUSION: The fact that obese subjects with MC4R mutations show an inverse relationship between obesity and MSNA suggests that central sympathetic outflow to the vasculature might depend on functional melanocortinergic pathways. Their dysfunction could explain reduced sympathoexcitability, lower sympathetic nerve-induced lipolysis, and the fact that blood pressure is rarely elevated in this type of obesity.

Effects of selective slow-wave sleep deprivation on nocturnal blood pressure dipping and daytime blood pressure regulation.

Nocturnal blood pressure (BP) decline or "dipping" is an active, central, nervously governed process, which is important for BP regulation during daytime. It is, however, not known whether the sleep process itself or, more specifically, slow-wave sleep (SWS) is important for normal dipping. Therefore, in the present study, healthy subjects (6 females, 5 males) were selectively deprived of SWS by EEG-guided acoustic arousals. BP and heart rate (HR) were monitored during experimental nights and the following day. Additionally, nocturnal catecholamine excretion was determined, and morning baroreflex function was assessed by microneurographic measurements of muscle sympathetic nerve activity (MSNA) and heart rate variability (HRV). Data were compared with a crossover condition of undisturbed sleep. SWS was successfully deprived leading to significantly attenuated mean arterial BP dipping during the first half (P < 0.05), but not during the rapid-eye-movement-dominated second half of total sleep; however, dipping still evolved even in the absence of SWS. No differences were found for nighttime catecholamine excretion. Moreover, daytime resting and ambulatory BP and HR were not altered, and morning MSNA and HRV did not differ significantly, indicating that baroreflex-mediated sympathoneural BP regulation was not affected by the preceding SWS deprivation. We conclude that in healthy humans the magnitude of nocturnal BP dipping is significantly affected by sleep depth. Deprivation of SWS during one night does not modulate the morning threshold and sensitivity of the vascular and cardiac baroreflex and does not alter ambulatory BP during daytime.

Insulin and metformin regulate circulating and adipose tissue chemerin.

OBJECTIVE: To assess chemerin levels and regulation in sera and adipose tissue from women with polycystic ovary syndrome (PCOS) and matched control subjects. RESEARCH DESIGN AND METHODS: Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of chemerin. Serum chemerin was measured by enzyme-linked immunosorbent assay. We investigated the in vivo effects of insulin on serum chemerin levels via a prolonged insulin-glucose infusion. Ex vivo effects of insulin, metformin, and steroid hormones on adipose tissue chemerin protein production and secretion into conditioned media were assessed by Western blotting and enzyme-linked immunosorbent assay, respectively. RESULTS: Serum chemerin, subcutaneous, and omental adipose tissue chemerin were significantly higher in women with PCOS (n = 14; P < 0.05, P < 0.01). Hyperinsulinemic induction in human subjects significantly increased serum chemerin levels (n = 6; P < 0.05, P < 0.01). In adipose tissue explants, insulin significantly increased (n = 6; P < 0.05, P < 0.01) whereas metformin significantly decreased (n = 6; P < 0.05, P < 0.01) chemerin protein production and secretion into conditioned media, respectively. After 6 months of metformin treatment, there was a significant decrease in serum chemerin (n = 21; P < 0.01). Importantly, changes in homeostasis model assessment-insulin resistance were predictive of changes in serum chemerin (P = 0.046). CONCLUSIONS: Serum and adipose tissue chemerin levels are increased in women with PCOS and are upregulated by insulin. Metformin treatment decreases serum chemerin in these women.

Metformin decreases angiogenesis via NF-kappaB and Erk1/2/Erk5 pathways by increasing the antiangiogenic thrombospondin-1.

AIMS: Polycystic ovary syndrome (PCOS) is associated with insulin resistance (IR), obesity, and cardiovascular complications. Thrombospondin-1 (TSP-1) is a novel antiangiogenic adipokine highly expressed in obese insulin-resistant subjects. We sought to assess TSP-1 levels in adipose tissue (AT) from PCOS women and matched controls. The effects of metformin treatment on circulating TSP-1 levels in PCOS subjects, the effects of serum from normal and PCOS women on in vitro migration and angiogenesis before and after metformin treatment, and ex vivo regulation of AT TSP-1 by D-glucose were also studied. METHODS AND RESULTS: Serum TSP-1 (ELISA), subcutaneous and omental AT TSP-1 mRNA (reverse transcriptase-polymerase chain reaction), and protein (western blotting) were significantly lower in PCOS women (P < 0.05). Corresponding plasminogen activator inhibitor-1 (PAI-1) and PAI-1 activity were significantly higher (P < 0.01). After 6 months of metformin treatment, there was a significant increase in serum TSP-1 (P < 0.05) and a corresponding decrease in PAI-1 and PAI-1 activity (P < 0.01). In vitro migration and angiogenesis were significantly increased in serum from PCOS women (P < 0.01); these effects were significantly attenuated by metformin treatment (P < 0.01) through the regulation of TSP-1 levels via nuclear factor-kappaB (NF-kappaB), extracellular regulated-signal kinase 1/2 (Erk1/2) and Erk5 pathways. Importantly, changes in the intima media thickness were predictive of changes in serum TSP-1 (P = 0.049). In AT explants, glucose significantly decreased TSP-1 protein production and secretion into conditioned media (ELISA) (P < 0.05, P < 0.001). CONCLUSION: TSP-1 levels are lower in PCOS women. Metformin treatment increases serum TSP-1 in these women. Our findings provide novel insights into the relationship between obesity, IR, and angiogenesis.

Cortisol and epinephrine control opposing circadian rhythms in T cell subsets.

Pronounced circadian rhythms in numbers of circulating T cells reflect a systemic control of adaptive immunity whose mechanisms are obscure. Here, we show that circadian variations in T cell subpopulations in human blood are differentially regulated via release of cortisol and catecholamines. Within the CD4(+) and CD8(+) T cell subsets, naive cells show pronounced circadian rhythms with a daytime nadir, whereas (terminally differentiated) effector CD8(+) T cell counts peak during daytime. Naive T cells were negatively correlated with cortisol rhythms, decreased after low-dose cortisol infusion, and showed highest expression of CXCR4, which was up-regulated by cortisol. Effector CD8(+) T cells were positively correlated with epinephrine rhythms, increased after low-dose epinephrine infusion, and showed highest expression of beta-adrenergic and fractalkine receptors (CX3CR1). Daytime increases in cortisol via CXCR4 probably act to redistribute naive T cells to bone marrow, whereas daytime increases in catecholamines via beta-adrenoceptors and, possibly, a suppression of fractalkine signaling promote mobilization of effector CD8(+) T cells from the marginal pool. Thus, activation of the major stress hormones during daytime favor immediate effector defense but diminish capabilities for initiating adaptive immune responses.

Metformin decreases the adipokine vaspin in overweight women with polycystic ovary syndrome concomitant with improvement in insulin sensitivity and a decrease in insulin resistance.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Vaspin (visceral adipose tissue-derived serine protease inhibitor) levels increase with hyperinsulinemia and obesity. Currently, no data exists on vaspin in PCOS women. We therefore assessed mRNA and protein levels of vaspin, including circulating vaspin, from subcutaneous and omental adipose tissue of PCOS women and matched control subjects. Ex vivo regulation of adipose tissue vaspin and the effects of metformin treatment on circulating vaspin levels in PCOS subjects were also studied. RESEARCH DESIGN AND METHODS: Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of vaspin. Serum vaspin was quantified by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue vaspin were analyzed ex vivo. RESULTS: There were significantly higher levels of circulating vaspin (P < 0.05), vaspin mRNA (P < 0.05), and protein (P < 0.05) in omental adipose tissue of PCOS women. Interestingly, in omental adipose tissue explants, glucose significantly increased vaspin protein levels and secretion into conditioned media (P < 0.001). Also, after 6 months of metformin treatment, there was a significant decrease in serum vaspin levels in PCOS women (P < 0.001). Furthermore, multivariate regression analysis revealed that following metformin therapy, changes in circulating glucose levels were predictive of changes in serum vaspin levels (P = 0.014). CONCLUSIONS: We report, for the first time, elevated serum and omental adipose tissue levels of vaspin in overweight PCOS women and ex vivo regulation of vaspin, predominantly by glucose. More importantly, metformin treatment decreases serum vaspin levels, a novel observation.

Asymmetrical dimethylarginine, inflammatory and metabolic parameters in women with polycystic ovary syndrome before and after metformin treatment.

CONTEXT: Insulin resistance plays a significant role in the pathogenesis of the polycystic ovary syndrome (PCOS) and represents a link to the unfavorable cardiovascular risk profile frequently found in affected patients. The endogenous nitric oxide synthase inhibitor asymmetrical dimethyl-L-arginine (ADMA) is associated with atherosclerosis and represents an independent marker for cardiovascular morbidity and mortality. OBJECTIVE: We investigated ADMA levels among other cardiovascular, metabolic, and hormonal parameters in women with PCOS and the effects of metformin treatment on these parameters. DESIGN: A cross-sectional study and clinical trial were performed. PATIENTS AND PARTICIPANTS: Women with PCOS (n = 83) compared with a control group of healthy women (n = 39) were studied. INTERVENTIONS: In a subgroup of patients with PCOS (n = 21), the effect of metformin was assessed after 6 months of treatment. MAIN OUTCOME MEASURES: ADMA, intima media thickness (IMT), metabolic and hormonal parameters, and markers of inflammation were investigated. RESULTS: ADMA levels were significantly higher in the PCOS group compared with controls (0.57 +/- 0.15 vs. 0.50 +/- 0.11; P = 0.024). Androgens, C-reactive protein, fasting C-peptide, area under the curve (AUC) insulin, AUC glucose, homeostatic assessment of insulin resistance, fasting insulin, glycosylated hemoglobin, cholesterol, low-density lipoprotein cholesterol, triglycerides, and IMT were significantly higher in women with PCOS compared with controls. In PCOS patients ADMA was found to be positively correlated with body mass index (BMI), waist to hip ratio, parameters of insulin sensitivity, hyperandrogenemia (free testosterone, free androgen index), and IMT. Treatment with metformin ameliorated hyperandrogenemia and decreased ADMA levels (0.53 +/- 0.06 vs. 0.46 +/- 0.09, P = 0.013). Decrease in ADMA levels subsequent to metformin treatment did not correlate with change in BMI or metabolic parameters. CONCLUSIONS: ADMA amd parameters of insulin sensitivity are elevated in women with PCOS and the degree of insulin resistance confers the greatest influence on ADMA level. Metformin treatment led to improvement of hormonal and metabolic parameters and decreased ADMA levels possibly independent of BMI and metabolic changes.