Apo AI Nanoparticles Delivered Post Myocardial Infarction Moderate Inflammation.

RATIONALE: Decades of research have examined immune-modulatory strategies to protect the heart after an acute myocardial infarction and prevent progression to heart failure but have failed to translate to clinical benefit. OBJECTIVE: To determine anti-inflammatory actions of n-apo AI (Apo AI nanoparticles) that contribute to cardiac tissue recovery after myocardial infarction. METHODS AND RESULTS: Using a preclinical mouse model of myocardial infarction, we demonstrate that a single intravenous bolus of n-apo AI (CSL111, 80 mg/kg) delivered immediately after reperfusion reduced the systemic and cardiac inflammatory response. N-apo AI treatment lowered the number of circulating leukocytes by 30±7% and their recruitment into the ischemic heart by 25±10% (all P<5.0×10-2). This was associated with a reduction in plasma levels of the clinical biomarker of cardiac injury, cardiac troponin-I, by 52±17% (P=1.01×10-2). N-apo AI reduced the cardiac expression of chemokines that attract neutrophils and monocytes by 60% to 80% and lowered surface expression of integrin CD11b on monocytes by 20±5% (all P<5.0×10-2). Fluorescently labeled n-apo AI entered the infarct and peri-infarct regions and colocalized with cardiomyocytes undergoing apoptosis and with leukocytes. We further demonstrate that n-apo AI binds to neutrophils and monocytes, with preferential binding to the proinflammatory monocyte subtype and partially via SR-BI (scavenger receptor BI). In patients with type 2 diabetes, we also observed that intravenous infusion of the same n-apo AI (CSL111, 80 mg/kg) similarly reduced the level of circulating leukocytes by 12±5% (all P<5.0×10-2). CONCLUSIONS: A single intravenous bolus of n-apo AI delivered immediately post-myocardial infarction reduced the systemic and cardiac inflammatory response through direct actions on both the ischemic myocardium and leukocytes. These data highlight the anti-inflammatory effects of n-apo AI and provide preclinical support for investigation of its use for management of acute coronary syndromes in the setting of primary percutaneous coronary interventions.

Preoperative biomarker evaluation for the prediction of cardiovascular events after major vascular surgery.

OBJECTIVE: The cause of perioperative myocardial infarction (PMI) is postulated to involve hemodynamic stress or coronary plaque destabilization. We aimed to evaluate perioperative factors in patients with peripheral artery disease (PAD) undergoing major vascular surgery to determine the likely mechanisms and predictors of PMI. METHODS: This was a prospective cohort study of 133 patients undergoing major vascular surgery including open abdominal aortic aneurysm (AAA) repair (n = 40) and major suprainguinal or infrainguinal arterial bypasses (non-AAA; n = 93). Preoperative assessment with history, physical examination, and peripheral artery tonometry was performed in addition to plasma sampling of biomarkers associated with inflammation and coronary plaque instability. The primary outcome was occurrence of a 30-day cardiovascular event (CVE; composite of PMI [troponin I elevation >99th percentile reference of ≥0.1 µg/L], stroke, or death). RESULTS: Of 133 patients, 36 patients (27%) developed a 30-day CVE after vascular surgery, and all were PMI. Patients with 30-day CVE were older (75 ± 8 years vs 69 ± 10 years, mean ± standard deviation; P = .001), had higher prevalence of hypertension (94% vs 79%; P = .01) and preoperative beta-blocker therapy (50% vs 29%; P = .02), and had longer duration of surgery (5.1 ± 1.8 hours vs 4.0 ± 1.1 hours; P < .0001). Significant elevations in cystatin C, N-terminal pro-B-type natriuretic peptide (NT-proBNP), troponin I, high-sensitivity troponin T, matrix metalloproteinase 3, and osteoprotegerin occurred in those who developed 30-day CVE (all P < .05). Multivariate binary logistic regression identified AAA surgery and log-transformed NT-proBNP to be independent preoperative predictors of 30-day CVE (area under the receiver operating characteristic curve = 0.81). CONCLUSIONS: In patients with peripheral artery disease undergoing major vascular surgery, the likely mechanism of PMI appears to be the hemodynamic stress related to the type and duration of surgery. NT-proBNP was a useful independent predictor of CVE and thus may serve as an important biomarker of cardiovascular fitness for surgery.

Potential vascular mechanisms of ramipril induced increases in walking ability in patients with intermittent claudication.

RATIONALE: We recently reported that ramipril more than doubled maximum walking times in patients with peripheral artery disease with intermittent claudication. OBJECTIVE: Our aim was to conduct exploratory analyses of the effects of ramipril therapy on circulating biomarkers of angiogenesis/arteriogenesis, thrombosis, inflammation, and leukocyte adhesion in patients with intermittent claudication. METHODS AND RESULTS: One hundred sixty-five patients with intermittent claudication (mean, 65.3 [SD, 6.7] years) were administered ramipril 10 mg per day (n=82) or matching placebo (n=83) for 24 weeks in a randomized, double-blind study. Plasma biomarkers of angiogenesis/arteriogenesis (vascular endothelial growth factor-A, fibroblast growth factor-2), thrombosis (D-dimer, von Willebrand factor, thrombin-antithrombin III), inflammation (high-sensitivity C-reactive protein, osteopontin), and leukocyte adhesion (soluble vascular cell adhesion molecule-1, soluble intracellular adhesion molecule-1) were measured at baseline and 24 weeks. Relative to placebo, ramipril was associated with increases in vascular endothelial growth factor-A by 38% (95% confidence interval [CI], 34%-42%) and fibroblast growth factor-2 by 64% (95% CI, 44-85%; P<0.001 for both), and reductions in D-dimer by 24% (95% CI, -30% to -18%), von Willebrand factor by 22% (95% CI, -35% to -9%), thrombin-antithrombin III by 16% (95% CI, -19% to -13%), high-sensitivity C-reactive protein by 13% (95% CI, -14% to -9%), osteopontin by 12% (95% CI, -14% to -10%), soluble vascular cell adhesion molecule-1 by 14% (95% CI, -18% to -10%), and soluble intracellular adhesion molecule-1 by 15% (95% CI, -17% to -13%; all P<0.001). With the exception of von Willebrand factor, all the above changes correlated significantly with the change in maximum walking time (P=0.02-0.001) in the group treated with ramipril. CONCLUSIONS: Ramipril is associated with an increase in the biomarkers of angiogenesis/arteriogenesis and reduction in the markers of thrombosis, inflammation, and leukocyte adhesion. This study informs strategies to improve mobility in patients with intermittent claudication. CLINICAL TRIAL REGISTRATION INFORMATION URL: http://clinicaltrials.gov. Unique identifier: NCT00681226.

Effects of high-density lipoprotein elevation with cholesteryl ester transfer protein inhibition on insulin secretion.

RATIONALE: High-density lipoprotein cholesterol elevation via cholesteryl ester transfer protein (CETP) inhibition represents a novel therapy for atherosclerosis, which also may have relevance for type 2 diabetes mellitus. OBJECTIVE: The current study assessed the effects of a CETP inhibitor on postprandial insulin, ex vivo insulin secretion, and cholesterol efflux from pancreatic ß-cells. METHODS AND RESULTS: Healthy participants received a daily dose of CETP inhibitor (n=10) or placebo (n=15) for 14 days in a randomized double-blind study. Insulin secretion and cholesterol efflux from MIN6N8 ß-cells were determined after incubation with treated plasma. CETP inhibition increased plasma high-density lipoprotein cholesterol, apolipoprotein AI, and postprandial insulin. MIN6N8 ß-cells incubated with plasma from CETP inhibitor-treated individuals (compared with placebo) exhibited an increase in both glucose-stimulated insulin secretion and cholesterol efflux over the 14-day treatment period. CONCLUSIONS: CETP inhibition increased postprandial insulin and promoted ex vivo ß-cell glucose-stimulated insulin secretion, potentially via enhanced ß-cell cholesterol efflux.

Reconstituted high-density lipoprotein infusion modulates fatty acid metabolism in patients with type 2 diabetes mellitus.

We recently demonstrated that reconstituted high-density lipoprotein (rHDL) modulates glucose metabolism in humans via both AMP-activated protein kinase (AMPK) in muscle and by increasing plasma insulin. Given the key roles of both AMPK and insulin in fatty acid metabolism, the current study investigated the effect of rHDL infusion on fatty acid oxidation and lipolysis. Thirteen patients with type 2 diabetes received separate infusions of rHDL and placebo in a randomized, cross-over study. Fatty acid metabolism was assessed using steady-state tracer methodology, and plasma lipids were measured by mass spectrometry (lipidomics). In vitro studies were undertaken in 3T3-L1 adipocytes. rHDL infusion inhibited fasting-induced lipolysis (P = 0.03), fatty acid oxidation (P < 0.01), and circulating glycerol (P = 0.04). In vitro, HDL inhibited adipocyte lipolysis in part via activation of AMPK, providing a possible mechanistic link for the apparent reductions in lipolysis observed in vivo. In contrast, circulating NEFA increased after rHDL infusion (P < 0.01). Lipidomic analyses implicated phospholipase hydrolysis of rHDL-associated phosphatidylcholine as the cause, rather than lipolysis of endogenous fat stores. rHDL infusion inhibits fasting-induced lipolysis and oxidation in patients with type 2 diabetes, potentially through both AMPK activation in adipose tissue and elevation of plasma insulin. The phospholipid component of rHDL also has the potentially undesirable effect of increasing circulating NEFA.

High-density lipoprotein modulates glucose metabolism in patients with type 2 diabetes mellitus.

BACKGROUND: Low plasma high-density lipoprotein (HDL) is associated with elevated cardiovascular risk and aspects of the metabolic syndrome. We hypothesized that HDL modulates glucose metabolism via elevation of plasma insulin and through activation of the key metabolic regulatory enzyme, AMP-activated protein kinase, in skeletal muscle. METHODS AND RESULTS: Thirteen patients with type 2 diabetes mellitus received both intravenous reconstituted HDL (rHDL: 80 mg/kg over 4 hours) and placebo on separate days in a double-blind, placebo-controlled crossover study. A greater fall in plasma glucose from baseline occurred during rHDL than during placebo (at 4 hours rHDL=-2.6+/-0.4; placebo=-2.1+/-0.3 mmol/L; P=0.018). rHDL increased plasma insulin (at 4 hours rHDL=3.4+/-10.0; placebo= -19.2+/-7.4 pmol/L; P=0.034) and also the homeostasis model assessment beta-cell function index (at 4 hours rHDL=18.9+/-5.9; placebo=8.6+/-4.4%; P=0.025). Acetyl-CoA carboxylase beta phosphorylation in skeletal muscle biopsies was increased by 1.7+/-0.3-fold after rHDL, indicating activation of the AMP-activated protein kinase pathway. Both HDL and apolipoprotein AI increased glucose uptake (by 177+/-12% and 144+/-18%, respectively; P<0.05 for both) in primary human skeletal muscle cell cultures established from patients with type 2 diabetes mellitus (n=5). The mechanism is demonstrated to include stimulation of the ATP-binding cassette transporter A1 with subsequent activation of the calcium/calmodulin-dependent protein kinase kinase and the AMP-activated protein kinase pathway. CONCLUSIONS: rHDL reduced plasma glucose in patients with type 2 diabetes mellitus by increasing plasma insulin and activating AMP-activated protein kinase in skeletal muscle. These findings suggest a role for HDL-raising therapies beyond atherosclerosis to address type 2 diabetes mellitus.

The effect of the nitric oxide donor sodium nitroprusside on glucose uptake in human primary skeletal muscle cells.

Nitric oxide (NO) has been implicated as an important signaling molecule in the insulin-independent, contraction-mediated glucose uptake pathway and may represent a novel strategy for blood glucose control in patients with type 2 diabetes (T2DM). The current study sought to determine whether the NO donor, sodium nitroprusside (SNP) increases glucose uptake in primary human skeletal muscle cells (HSkMC) derived from both healthy individuals and patients with T2DM. Vastus lateralis muscle cell cultures were derived from seven males with T2DM (aged 54 +/-2 years, BMI 31.7 +/-1.2 kg/m(2), fasting plasma glucose 9.52+/-0.80 mmol/L) and eight healthy individuals (aged 46 +/-2 years, BMI 27.1 +/- 1.5 kg/m(2), fasting plasma glucose 4.69+/-0.12 mmol/L). Cultures were treated with both therapeutic (0.2 and 2 microM) and supratherapeutic (3, 10 and 30 mM) concentrations of SNP. An additional NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP) was also examined at a concentration of 50 microM. Glucose uptake was significantly increased following both 30 and 60 min incubations with the supratherapeutic SNP treatments (P=0.03) but not the therapeutic SNP doses (P=0.60) or SNAP (P=0.54). There was no difference in the response between the healthy and T2DM cell lines with any treatment or dose. The current study demonstrates that glucose uptake is elevated by supratherapeutic, but not therapeutic doses of SNP in human primary skeletal muscle cells derived from both healthy volunteers and patients with T2D. These data confirm that nitric oxide donors have potential therapeutic utility to increase glucose uptake in humans, but that SNP only achieves this in supratherapeutic doses. Further study to delineate mechanisms and the therapeutic window is warranted.

MicroRNA-194 Modulates Glucose Metabolism and Its Skeletal Muscle Expression Is Reduced in Diabetes.

BACKGROUND: The regulation of microRNAs (miRNAs) at different stages of the progression of type 2 diabetes mellitus (T2DM) and their role in glucose homeostasis was investigated. METHODS: Microarrays were used to assess miRNA expression in skeletal muscle biopsies taken from healthy individuals and patients with pre-diabetes or T2DM, and insulin resistant offspring of rat dams fed a high fat diet during pregnancy. RESULTS: Twenty-three miRNAs were differentially expressed in patients with T2DM, and 7 in the insulin resistant rat offspring compared to their controls. Among these, only one miRNA was similarly regulated: miR-194 expression was significantly reduced by 25 to 50% in both the rat model and in human with pre-diabetes and established diabetes. Knockdown of miR-194 in L6 skeletal muscle cells induced an increase in basal and insulin-stimulated glucose uptake and glycogen synthesis. This occurred in conjunction with an increased glycolysis, indicated by elevated lactate production. Moreover, oxidative capacity was also increased as we found an enhanced glucose oxidation in presence of the mitochondrial uncoupler FCCP. When miR-194 was down-regulated in vitro, western blot analysis showed an increased phosphorylation of AKT and GSK3ß in response to insulin, and an increase in expression of proteins controlling mitochondrial oxidative phosphorylation. CONCLUSIONS: Type 2 diabetes mellitus is associated with regulation of several miRNAs in skeletal muscle. Interestingly, miR-194 was a unique miRNA that appeared regulated across different stages of the disease progression, from the early stages of insulin resistance to the development of T2DM. We have shown miR-194 is involved in multiple aspects of skeletal muscle glucose metabolism from uptake, through to glycolysis, glycogenesis and glucose oxidation, potentially via mechanisms involving AKT, GSK3 and oxidative phosphorylation. MiR-194 could be down-regulated in patients with early features of diabetes as an adaptive response to facilitate tissue glucose uptake and metabolism in the face of insulin resistance.

Frequent interruptions of sedentary time modulates contraction- and insulin-stimulated glucose uptake pathways in muscle: Ancillary analysis from randomized clinical trials.

Epidemiological studies have observed associations between frequent interruptions of sitting time with physical activity bouts and beneficial metabolic outcomes, even in individuals who regularly exercise. Frequent interruptions to prolonged sitting reduce postprandial plasma glucose. Here we studied potential skeletal muscle mechanisms accounting for this improved control of glycemia in overweight adults under conditions of one day uninterrupted sitting and sitting interrupted with light-intensity or moderate-intensity walking every 20-min (n = 8); and, after three days of either uninterrupted sitting or light-intensity walking interruptions (n = 5). Contraction- and insulin-mediated glucose uptake signaling pathways as well as changes in oxidative phosphorylation proteins were examined. We showed that 1) both interventions reduce postprandial glucose concentration, 2) acute interruptions to sitting over one day stimulate the contraction-mediated glucose uptake pathway, 3) both acute interruptions to sitting with moderate-intensity activity over one day and light-intensity activity over three days induce a transition to modulation of the insulin-signaling pathway, in association with increased capacity for glucose transport. Only the moderate-intensity interruptions resulted in greater capacity for glycogen synthesis and likely for ATP production. These observations contribute to a mechanistic explanation of improved postprandial glucose metabolism with regular interruptions to sitting time, a promising preventive strategy for metabolic diseases.

Effects of the BET-inhibitor, RVX-208 on the HDL lipidome and glucose metabolism in individuals with prediabetes: A randomized controlled trial.

AIMS: High-density lipoprotein (HDL) and apolipoprotein A-I (apoA-I) can modulate glucose metabolism through multiple mechanisms. This study determined the effects of a novel bromodomain and extra-terminal (BET) inhibitor (RVX-208) and putative apoA-I inducer on lipid species contained within HDL (HDL lipidome) and glucose metabolism. MATERIALS AND METHODS: Twenty unmedicated males with prediabetes received 100mg b.i.d. RVX-208 and placebo for 29-33days separated by a wash-out period in a randomized, cross-over design trial. Plasma HDL-cholesterol and apoA-I were assessed as well as lipoprotein particle size and distribution using NMR spectroscopy. An oral glucose tolerance test (OGTT) protocol with oral and infused stable isotope tracers was employed to assess postprandial plasma glucose, indices of insulin secretion and insulin sensitivity, glucose kinetics and lipolysis. Whole plasma and HDL lipid profiles were measured using mass spectrometry. RESULTS: RVX-208 treatment for 4weeks increased 6 sphingolipid and 4 phospholipid classes in the HDL lipidome (p≤0.05 versus placebo), but did not change conventional clinical lipid measures. The concentration of medium-sized HDL particles increased by 11% (P=0.01) and small-sized HDL particles decreased by 10% (P=0.04) after RVX-208 treatment. In response to a glucose load, after RVX-208 treatment, plasma glucose peaked at a similar level to placebo, but 30min later with a more sustained elevation (treatment effect, P=0.003). There was a reduction and delay in total (P=0.001) and oral (P=0.003) glucose rates of appearance in plasma and suppression of endogenous glucose production (P=0.014) after RVX-208 treatment. The rate of glucose disappearance was also lower following RVX-208 (P=0.016), with no effect on glucose oxidation or total glucose disposal. CONCLUSIONS: RVX-208 increased 10 lipid classes in the plasma HDL fraction, without altering the concentrations of either apoA-I or HDL-cholesterol (HDL-C). RVX-208 delayed and reduced oral glucose absorption and endogenous glucose production, with plasma glucose maintained via reduced peripheral glucose disposal. If sustained, these effects may protect against the development of type 2 diabetes.

Reduced UCP-1 content in in vitro differentiated beige/brite adipocytes derived from preadipocytes of human subcutaneous white adipose tissues in obesity.

INTRODUCTION: Brown adipose tissue (BAT) is a potential therapeutic target to reverse obesity. The purpose of this study was to determine whether primary precursor cells isolated from human adult subcutaneous white adipose tissue (WAT) can be induced to differentiate in-vitro into adipocytes that express key markers of brown or beige adipose, and whether the expression level of such markers differs between lean and obese young adult males. METHODS: Adipogenic precursor cells were isolated from lean and obese individuals from subcutaneous abdominal WAT biopsies. Cells were grown to confluence, differentiated for 2.5 weeks then harvested for measurement of gene expression and UCP1 protein. RESULTS: There was no difference between groups with respect to differentiation into adipocytes, as indicated by oil red-O staining, rates of lipolysis, and expression of adipogenic genes (FABP4, PPARG). WAT genes (HOXC9, RB1) were expressed equally in the two groups. Post differentiation, the beige adipose specific genes CITED1 and CD137 were significantly increased in both groups, but classic BAT markers ZIC1 and LHX8 decreased significantly. Cell lines from both groups also equally increased post-differentiation expression of the thermogenic-responsive gene PPARGC1A (PGC-1α). UCP1 gene expression was undetectable prior to differentiation, however after differentiation both gene expression and protein content were increased in both groups and were significantly greater in cultures from lean compared with obese individuals (p<0.05). CONCLUSION: Human subcutaneous WAT cells can be induced to attain BAT characteristics, but this capacity is reduced in WAT cells from obese individuals.

Skeletal muscle insulin resistance associated with cholesterol-induced activation of macrophages is prevented by high density lipoprotein.

BACKGROUND: Emerging evidence suggests that high density lipoprotein (HDL) may modulate glucose metabolism through multiple mechanisms including pancreatic insulin secretion as well as insulin-independent glucose uptake into muscle. We hypothesized that HDL may also increase skeletal muscle insulin sensitivity via cholesterol removal and anti-inflammatory actions in macrophages associated with excess adiposity and ectopic lipid deposition. METHODS: Human primary and THP-1 macrophages were treated with vehicle (PBS) or acetylated low density lipoprotein (acLDL) with or without HDL for 18 hours. Treatments were then removed, and macrophages were incubated with fresh media for 4 hours. This conditioned media was then applied to primary human skeletal myotubes derived from vastus lateralis biopsies taken from patients with type 2 diabetes to examine insulin-stimulated glucose uptake. RESULTS: Conditioned media from acLDL-treated primary and THP-1 macrophages reduced insulin-stimulated glucose uptake in primary human skeletal myotubes compared with vehicle (primary macrophages, 168±21% of basal uptake to 104±19%; THP-1 macrophages, 142±8% of basal uptake to 108±6%; P<0.05). This was restored by co-treatment of macrophages with HDL. While acLDL increased total intracellular cholesterol content, phosphorylation of c-jun N-terminal kinase and secretion of pro- and anti-inflammatory cytokines from macrophages, none were altered by co-incubation with HDL. Insulin-stimulated Akt phosphorylation in human skeletal myotubes exposed to conditioned media was unaltered by either treatment condition. CONCLUSION: Inhibition of insulin-stimulated glucose uptake in primary human skeletal myotubes by conditioned media from macrophages pre-incubated with acLDL was restored by co-treatment with HDL. However, these actions were not linked to modulation of common pro- or anti-inflammatory mediators or insulin signaling via Akt.

Effect of iron chelation on myocardial infarct size and oxidative stress in ST-elevation-myocardial infarction.

BACKGROUND: Experimental studies suggest that deferoxamine (DFO) limits the generation of reactive oxygen species by chelating redox-active iron and thereby may reduce ischemia-reperfusion injury and myocardial infarct (MI) size. We investigated whether DFO administered before reperfusion by primary percutaneous coronary intervention (PPCI) would ameliorate oxidative stress and MI size. METHODS AND RESULTS: We randomly assigned 60 patients with ST-elevation-MI to receive an intravenous bolus of DFO (500 mg) immediately before PPCI followed by a 12-hour infusion (50 mg/kg of body weight) (n=28) or normal saline bolus and infusion (placebo group, n=32). MI size was measured by contrast-enhanced cardiac MRI (CMRI; day 3±1), creatine kinase and troponin I area-under-the-curve, and severity of wall motion abnormality on echocardiography. Clinical follow-up including repeat CMRI and echocardiography were performed at 3 months (100±17 days). Oxidative stress was assessed by plasma F(2)-isoprostane levels. DFO and placebo groups were well balanced with respect to baseline characteristics, symptom- and door-to-balloon times, pre-PPCI coronary patency, and infarct-related artery location. Serum iron levels were decreased with DFO treatment after PPCI compared with placebo (3.0±2.5 versus 12.6±5.5 µmol/L, P<0.0001), which persisted until the end of the infusion. In DFO-treated patients, there was a significant reduction in plasma F(2)-isoprostane levels immediately after PPCI (2878±1461 versus 2213±579 pmol/L, P=0.04). However, there was no difference in CMRI-determined infarct size (DFO, 17.4±10.8%, versus placebo, 18.6±10.2%; P=0.73), myocardial salvage index at 3 days or at 3 months, or the area-under-the-curve for creatine kinase or troponin I. CONCLUSIONS: Adjunctive DFO treatment after the onset of ischemia and continued periprocedurally ameliorates oxidative stress without limiting infarct size. CLINICAL TRIAL REGISTRATION: URL: http://www.anzctr.org.au/. Unique identifier: ACTRN12608000308392.

Ramipril reduces large-artery stiffness in peripheral arterial disease and promotes elastogenic remodeling in cell culture.

Ramipril improves cardiovascular outcome in patients with peripheral arterial disease; however, the precise mechanisms of benefit remain to be elucidated. The effect of ramipril on large-artery stiffness in patients with peripheral arterial disease was examined. In addition, we determined the effect of ramiprilat on extracellular matrix from human aortic smooth muscle cell culture. Forty patients with peripheral arterial disease were randomized to receive ramipril, 10 mg once daily or placebo for 24 weeks. Arterial stiffness was assessed globally via systemic arterial compliance and augmentation index (carotid tonometry and Doppler velocimetry), and regionally via carotid-femoral pulse wave velocity. Angiotensin-converting enzyme inhibition increased arterial compliance by 0.10+/-0.02 mL/mm Hg, (P<0.001, all probability values relative to placebo) and reduced pulse wave velocity by 1.7+/-0.2 m/s (P<0.001), augmentation index by 4.1+/-0.3% (P<0.001), and systolic blood pressure by 5+/-1 mm Hg (P<0.001). Ramipril did not reduce mean arterial pressure significantly compared with placebo (P=0.59). In cell culture, ramiprilat decreased collagen deposition by >50% and increased elastin and fibrillin-1 deposition by >3- and 4-fold respectively (histochemistry and immunohistochemistry). Fibrillin-1 gene expression was increased 5-fold (real-time reverse-transcriptase polymerase chain reaction). Ramiprilat also reduced gene and protein (Western) expression of both matrix metalloproteinase (MMP)-2 and MMP-3. In conclusion, ramipril promoted an elastogenic matrix profile that may contribute to the observed clinical reduction in large-artery stiffness and carotid pressure augmentation, which occurred independently of mean arterial blood pressure reduction in patients with peripheral arterial disease.

Sex steroids modulate human aortic smooth muscle cell matrix protein deposition and matrix metalloproteinase expression.

Large artery stiffening increases cardiovascular risk and promotes isolated systolic hypertension which is more prevalent in elderly women than men. Variation in sex steroid levels between males and females and throughout life may modulate arterial stiffness. We hypothesized that sex steroids directly influence expression of important structural proteins which determine arterial biomechanical properties. Human aortic smooth muscle cells were incubated with physiological concentrations of 17beta-estradiol, progesterone, 17beta-estradiol and progesterone, or testosterone for 4 weeks. Collagen, elastin, and fibrillin-1 deposition was examined (histochemistry/immunohistochemistry). Gene and protein expression of 2 important matrix metalloproteinases (MMPs), MMPs 2 and 3, regulating matrix turnover was assessed. All sex steroids reduced collagen deposition relative to control (100%). However, the reduction was greater with female sex steroids than testosterone (control, 100%; 17beta-estradiol plus progesterone, 20+/-2%; testosterone 74+/-12%, P<0.001). Female sex steroids increased elastin deposition compared with control (control, 100%; 17beta-estradiol, 540+/-60%; progesterone, 290+/-40%; 17beta-estradiol plus progesterone, 400+/-80%, all P<0.01). The elastin/collagen ratio was >11-fold higher in the presence of 17beta-estradiol and progesterone compared with testosterone. Fibrillin-1 deposition was doubled in the presence of female sex steroids (17beta-estradiol plus progesterone) compared with testosterone (P<0.01). MMP-2 gene and protein expression was unaffected by any sex steroid. Testosterone increased both gene and protein expression of MMP-3 relative to both control and female sex steroids (P<0.01). This may contribute to degradation of elastic matrix proteins. In conclusion, female sex steroids promote an elastic matrix profile, which likely contributes to variation in large artery stiffness observed between sexes and with changes in hormonal status across the lifespan.