Rationale, design, and baseline characteristics of the CArdiovascular safety and Renal Microvascular outcomE study with LINAgliptin (CARMELINA®): a randomized, double-blind, placebo-controlled clinical trial in patients with type 2 diabetes and high cardio-renal risk.

BACKGROUND: Cardiovascular (CV) outcome trials in type 2 diabetes (T2D) have underrepresented patients with chronic kidney disease (CKD), leading to uncertainty regarding their kidney efficacy and safety. The CARMELINA® trial aims to evaluate the effects of linagliptin, a DPP-4 inhibitor, on both CV and kidney outcomes in a study population enriched for cardio-renal risk. METHODS: CARMELINA® is a randomized, double-blind, placebo-controlled clinical trial conducted in 27 countries in T2D patients at high risk of CV and/or kidney events. Participants with evidence of CKD with or without CV disease and HbA1c 6.5-10.0% (48-86 mmol/mol) were randomized 1:1 to receive linagliptin once daily or matching placebo, added to standard of care adjusted according to local guidelines. The primary outcome is time to first occurrence of CV death, non-fatal myocardial infarction, or non-fatal stroke. The key secondary outcome is a composite of time to first sustained occurrence of end-stage kidney disease, ≥ 40% decrease in estimated glomerular filtration rate (eGFR) from baseline, or renal death. CV and kidney events are prospectively adjudicated by independent, blinded clinical event committees. CARMELINA® was designed to continue until at least 611 participants had confirmed primary outcome events. Assuming a hazard ratio of 1.0, this provides 90% power to demonstrate non-inferiority of linagliptin versus placebo within the pre-specified non-inferiority margin of 1.3 at a one-sided α-level of 2.5%. If non-inferiority of linagliptin for the primary outcome is demonstrated, then its superiority for both the primary outcome and the key secondary outcome will be investigated with a sequentially rejective multiple test procedure. RESULTS: Between July 2013 and August 2016, 6980 patients were randomized and took ≥ 1 dose of study drug (40.6, 33.1, 16.9, and 9.4% from Europe, South America, North America, and Asia, respectively). At baseline, mean ± SD age was 65.8 ± 9.1 years, HbA1c 7.9 ± 1.0%, BMI 31.3 ± 5.3 kg/m2, and eGFR 55 ± 25 mL/min/1.73 m2. A total of 5148 patients (73.8%) had prevalent kidney disease (defined as eGFR < 60 mL/min/1.73 m2 or macroalbuminuria [albumin-to-creatinine ratio > 300 mg/g]) and 3990 patients (57.2%) had established CV disease with increased albuminuria; these characteristics were not mutually exclusive. Microalbuminuria (n = 2896 [41.5%]) and macroalbuminuria (n = 2691 [38.6%]) were common. CONCLUSIONS: CARMELINA® will add important information regarding the CV and kidney disease clinical profile of linagliptin by including an understudied, vulnerable cohort of patients with T2D at highest cardio-renal risk. Trial registration ClinicalTrials.gov identifier-NCT01897532; registered July 9, 2013.

Population Pharmacokinetics and Exposure-Response (Efficacy and Safety/Tolerability) of Empagliflozin in Patients with Type 2 Diabetes.

INTRODUCTION: The aim of the analysis was to characterize the population pharmacokinetics (PKs) and exposure-response (E-R) for efficacy (fasting plasma glucose, glycated hemoglobin) and safety/tolerability [hypoglycemia, genital infections, urinary tract infection (UTI), and volume depletion] of the sodium glucose cotransporter 2 inhibitor, empagliflozin, in patients with type 2 diabetes mellitus. This study extends the findings of previous analyses which described the PK and pharmacodynamics (PD) using early clinical studies of up to 12 weeks in duration. METHODS: Population pharmacokinetic and E-R models were developed based on two Phase I, four Phase II, and four Phase III studies. RESULTS: Variability in empagliflozin exposure was primarily affected by estimated glomerular filtration rate (eGFR) (less than twofold increase in exposure in patients with severe renal impairment). Consistent with its mode of action, the efficacy of empagliflozin was increased with elevated baseline plasma glucose levels and attenuated with decreasing renal function, but was still maintained to nearly half the maximal effect with eGFR as low as 30 mL/min/1.73 m(2). All other investigated covariates, including sex, body mass index, race, and age did not alter the PK or efficacy of empagliflozin to a clinically relevant extent. Compared with placebo, empagliflozin administration was associated with an exposure-independent increase in the incidence of genital infections and no significant change in the risk of UTI, hypoglycemia, or volume depletion. CONCLUSION: Based on the results from the PK and E-R analysis, no dose adjustment is required for empagliflozin in the patient population for which the drug is approved. FUNDING: Boehringer Ingelheim.

Safety and Tolerability of Empagliflozin in Patients with Type 2 Diabetes.

PURPOSE: The aim of this analysis was to establish the safety profile and tolerability of empagliflozin in patients with type 2 diabetes mellitus (T2DM) according to pooled data from several clinical trials. METHODS: Pooled data were analyzed from patients with T2DM treated with placebo (n = 3695), empagliflozin 10 mg (n = 3806), or empagliflozin 25 mg (n = 4782) in 17 randomized, Phase I, II, and III clinical trials plus 6 extension studies. Adverse events (AEs) were assessed descriptively in patients who took ≥1 dose of the study drug. AE incidence rates per 100 patient-years were calculated to adjust for differences in drug exposure across trials. FINDINGS: Total exposure was 3254, 3840, and 5649 patient-years in the placebo, empagliflozin 10 mg, and empagliflozin 25 mg groups, respectively. The incidence of any AEs, AEs leading to treatment discontinuation, severe AEs, and serious AEs was no higher in patients treated with empagliflozin than with placebo. Empagliflozin was not associated with an increased risk of hypoglycemia versus placebo, except in patients on background sulfonylurea and/or insulin. The incidence of events consistent with urinary tract infection was similar across treatment groups (9.4-11.3/100 patient-years); 0.4%, 0.2%, and 0.3% of patients in the placebo, empagliflozin 10 mg, and empagliflozin 25 mg groups, respectively, had urinary tract infections that required or prolonged hospitalization. The incidence of events consistent with genital infection was higher in patients treated with empagliflozin (4.7 and 5.0/100 patient-years for empagliflozin 10 and 25 mg, respectively) than placebo (1.3/100 patient-years), but only 0.1%, 0.1%, and <0.1% in the placebo, empagliflozin 10 mg, and empagliflozin 25 mg groups, respectively, had genital infections that required or prolonged hospitalization. The incidence of AEs consistent with volume depletion was similar with placebo, empagliflozin 10 mg, and empagliflozin 25 mg (1.6, 1.5, and 1.3/100 patient-years, respectively) and was higher with empagliflozin 25 mg than placebo or empagliflozin 10 mg in patients aged >75 years (4.4 vs 2.3 and 2.5/100 patient-years, respectively). The incidences of bone fractures, malignancies, decreased renal function, hepatic injury, venous thromboembolic events, and diabetic ketoacidosis were low and similar across the treatment groups. IMPLICATIONS: In this predefined analysis that was based on >9000 patient-years' exposure to empagliflozin, empagliflozin 10 mg, and empagliflozin 25 mg were well tolerated in patients with T2DM.

Effect of gemfibrozil, rifampicin, or probenecid on the pharmacokinetics of the SGLT2 inhibitor empagliflozin in healthy volunteers.

BACKGROUND: Empagliflozin is a potent, oral, selective inhibitor of sodium glucose cotransporter 2 in development for the treatment of type 2 diabetes mellitus. OBJECTIVE: The goal of these studies was to investigate potential drug-drug interactions between empagliflozin and gemfibrozil (an organic anion-transporting polypeptide 1B1 [OATP1B1]/1B3 and organic anion transporter 3 [OAT3] inhibitor), rifampicin (an OATP1B1/1B3 inhibitor), or probenecid (an OAT3 and uridine diphosphate glucuronosyltransferase inhibitor). METHODS: Two open-label, randomized, crossover studies were undertaken in healthy subjects. In the first study, 18 subjects received the following in 1 of 2 randomized treatment sequences: a single dose of empagliflozin 25 mg alone and gemfibrozil 600 mg BID for 5 days with a single dose of empagliflozin 25 mg on the third day. In the second study, 18 subjects received a single dose of empagliflozin 10 mg, a single dose of empagliflozin 10 mg coadministered with a single dose of rifampicin 600 mg, and probenecid 500 mg BID for 4 days with a single dose of empagliflozin 10 mg on the second day in 1 of 6 randomized treatment sequences. RESULTS: In the gemfibrozil study, 11 subjects were male, mean age was 35.1 years and mean body mass index (BMI) was 23.47 kg/m(2). In the rifampicin/probenecid study, 10 subjects were male, mean age was 32.7 years and mean BMI was 23.03 kg/m(2). Exposure to empagliflozin was increased by coadministration with gemfibrozil (AUC0-∞: geometric mean ratio [GMR], 158.50% [90% CI, 151.77-165.53]; Cmax: GMR, 115.00% [90% CI, 106.15-124.59]), rifampicin (AUC0-∞: GMR, 135.20% [90% CI, 129.58-141.06]; Cmax: GMR, 175.14% [90% CI, 160.14-191.56]), and probenecid (AUC0-∞: GMR, 153.47% [90% CI, 146.41-160.88]; Cmax: GMR, 125.60% [90% CI, 113.67-138.78]). All treatments were well tolerated. CONCLUSIONS: Increases in empagliflozin exposure were <2-fold, indicating that the inhibition of the OATP1B1/1B3, OAT3 transporter, and uridine diphosphate glucuronosyltransferases did not have a clinically relevant effect on empagliflozin exposure. No dose adjustments of empagliflozin were necessary when it was coadministered with gemfibrozil, rifampicin, or probenecid. ClinicalTrials.gov identifiers: NCT01301742 and NCT01634100.

Effect of empagliflozin on the steady-state pharmacokinetics of ethinylestradiol and levonorgestrel in healthy female volunteers.

BACKGROUND: Empagliflozin is a potent, selective inhibitor of sodium glucose cotransporter 2 in development for the treatment of patients with type 2 diabetes mellitus. Oral contraceptives may be co-administered with antidiabetic agents over long periods of time, therefore potential drug-drug interactions between oral contraceptives and antidiabetic drugs should be investigated. OBJECTIVE: The effect of multiple oral doses of empagliflozin 25 mg once daily (qd) on the steady-state pharmacokinetics of the combined oral contraceptive ethinylestradiol (EE) 30 µg/levonorgestrel (LNG) 150 µg qd was investigated. STUDY DESIGN: This was a phase I, open-label, two-period, fixed sequence study. SETTING: The study was performed at the Human Pharmacology Centre/Department of Translational Medicine, Boehringer Ingelheim, Biberach, Germany. PARTICIPANTS: Eighteen healthy premenopausal women participated in the study. INTERVENTION: There was a mandatory run-in period in which participants received EE 30 µg/LNG 150 µg qd for 21-48 days followed by a treatment-free interval of 7 days. Participants then received EE 30 µg/LNG 150 µg qd for 14 days (reference; period 1), followed by EE 30 µg/LNG 150 µg qd plus empagliflozin 25 mg qd for 7 days (test; period 2). MAIN OUTCOME MEASURES: The pharmacokinetics of EE and LNG at steady state based on the primary endpoints of area under the steady-state plasma concentration-time curve during a dosage interval τ (AUC(τ,ss)) and maximum steady-state plasma concentration during a dosage interval (C (max,ss)) were the main outcome measures. RESULTS: The pharmacokinetics of EE and LNG were not affected by co-administration with empagliflozin. Geometric mean ratios (90 % CI) of AUC(τ,ss) and C (max,ss) for EE were 102.82 % (97.58, 108.35) and 99.22 % (93.40, 105.39), respectively. For LNG, these values were 101.94 % (98.54, 105.47) and 105.81 % (99.47, 112.55), respectively. The 90 % CIs were within the standard bioequivalence boundaries of 80-125 %. There were no relevant changes in the time to reach peak levels (t (max,ss)) or terminal elimination half-life (t (½,ss)) of EE and LNG between test and reference treatments. Ten women in each treatment had at least one adverse event (AE). Severe AEs were reported by three women in the reference period and one woman in the test period. There were no serious AEs or premature discontinuations. CONCLUSION: The combination of EE 30 µg/LNG 150 µg and empagliflozin 25 mg was well tolerated. Based on standard bioequivalence criteria, empagliflozin had no effect on the pharmacokinetics of EE and LNG, indicating that no dose adjustment of EE 30 µg/LNG 150 µg is required when empagliflozin is co-administered.

Expression of human chemerin induces insulin resistance in the skeletal muscle but does not affect weight, lipid levels, and atherosclerosis in LDL receptor knockout mice on high-fat diet.

OBJECTIVE: Chemerin is a recently discovered hepatoadipokine that regulates adipocyte differentiation as well as chemotaxis and activation of dendritic cells and macrophages. Chemerin was reported to modulate insulin sensitivity in adipocytes and skeletal muscle cells in vitro and to exacerbate glucose intolerance in several mouse models in vivo. In humans, chemerin was shown to be associated with multiple components of the metabolic syndrome including BMI, triglycerides, HDL cholesterol, and hypertension. This study aimed to examine the effect of chemerin on weight, glucose and lipid metabolism, as well as atherosclerosis in vivo. RESEARCH DESIGN AND METHODS: We used recombinant adeno-associated virus to express human chemerin in LDL receptor knockout mice on high-fat diet. RESULTS: Expression of chemerin did not significantly alter weight, lipid levels, and extent of atherosclerosis. Chemerin, however, significantly increased glucose levels during the intraperitoneal glucose tolerance test without affecting endogenous insulin levels and the insulin tolerance test. Chemerin reduced insulin-stimulated Akt1 phosphorylation and activation of 5'AMP-activated protein kinase (AMPK) in the skeletal muscle, but had no effect on Akt phosphorylation and insulin-stimulated AMPK activation in the liver and gonadal adipose tissue. CONCLUSIONS: Chemerin induces insulin resistance in the skeletal muscle in vivo. Chemerin is involved in the cross talk between liver, adipose tissue, and skeletal muscle.

MMP-1 serum levels predict coronary atherosclerosis in humans.

BACKGROUND: Myocardial infarction results as a consequence of atherosclerotic plaque rupture, with plaque stability largely depending on the lesion forming extracellular matrix components. Lipid enriched non-calcified lesions are considered more instable and rupture prone than calcified lesions. Matrix metalloproteinases (MMPs) are extracellular matrix degrading enzymes with plaque destabilisating characteristics which have been implicated in atherogenesis. We therefore hypothesised MMP-1 and MMP-9 serum levels to be associated with non-calcified lesions as determined by CT-angiography in patients with coronary artery disease. METHODS: 260 patients with typical or atypical chest pain underwent dual-source multi-slice CT-angiography (0.6-mm collimation, 330-ms gantry rotation time) to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed or non-calcified. RESULTS: In multivariable regession analysis, MMP-1 serum levels were associated with total plaque burden (OR: 1.37 (CI: 1.02-1.85); p < 0.05) in a model adjusted for age, sex, BMI, classical cardiovascular risk factors, hsCRP, adiponectin, pericardial fat volume and medication. Specification of plaque morphology revealed significant association of MMP-1 serum levels with non-calcified plaques (OR: 1.16 (CI: 1.0-1.34); p = 0.05) and calcified plaques (OR: 1.22 (CI: 1,03-1.45); p < 0.05) while association with mixed plaques was lost in the fully adjusted model. No associations were found between MMP9 serum levels and total plaque burden or plaque morphology. CONCLUSION: MMP-1 serum levels are associated with total plaque burden but do not allow a specification of plaque morphology.

Chemerin is associated with markers of inflammation and components of the metabolic syndrome but does not predict coronary atherosclerosis.

OBJECTIVES: Chemerin is a recently discovered adipokine that regulates adipocyte differentiation and modulates chemotaxis and activation of dendritic cells and macrophages. Given the convergence of adipocyte and macrophage function, chemerin may provide an interesting link between obesity, inflammation and atherosclerosis in humans. We sought to examine the relationship of i) chemerin and markers of inflammation, ii) chemerin and components of the metabolic syndrome, and iii) chemerin and coronary atherosclerotic plaque burden and morphology. DESIGN: Serum chemerin levels were determined in 303 patients with stable typical or atypical chest pain who underwent dual-source multi-slice CT-angiography to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed, or non-calcified. RESULTS: Chemerin levels were highly correlated with high sensitivity C-reactive protein (r=0.44, P<0.0001), interleukin-6 (r=0.18, P=0.002), tumor necrosis factor-alpha (r=0.24, P<0.0001), resistin (r=0.28, P<0.0001), and leptin (r=0.36, P<0.0001) concentrations. Furthermore, chemerin was associated with components of the metabolic syndrome including body mass index (r=0.23, P=0.0002), triglycerides (r=0.29, P<0.0001), HDL-cholesterol (r=-0.18, P=0.003), and hypertension (P<0.0001). In bivariate analysis, chemerin levels were weakly correlated with coronary plaque burden (r=0.16, P=0.006) and the number of non-calcified plaques (r=0.14, P=0.02). These associations, however, were lost after adjusting for established cardiovascular risk factors (odds ratio, OR 1.17, 95% confidence interval (CI) 0.97-1.41, P=0.11 for coronary plaque burden; OR 1.06, 95% CI 0.96-1.17, P=0.22 for non-calcified plaques). CONCLUSIONS: Chemerin is strongly associated with markers of inflammation and components of the metabolic syndrome. However, chemerin does not predict coronary atherosclerosis.

Low adiponectin levels are an independent predictor of mixed and non-calcified coronary atherosclerotic plaques.

BACKGROUND: Atherosclerosis is the primary cause of coronary artery disease (CAD). There is increasing recognition that lesion composition rather than size determines the acute complications of atherosclerotic disease. Low serum adiponectin levels were reported to be associated with coronary artery disease and future incidence of acute coronary syndrome (ACS). The impact of adiponectin on lesion composition still remains to be determined. METHODOLOGY/PRINCIPAL FINDINGS: We measured serum adiponectin levels in 303 patients with stable typical or atypical chest pain, who underwent dual-source multi-slice CT-angiography to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed or non-calcified. In bivariate analysis adiponectin levels were inversely correlated with total coronary plaque burden (r = -0.21, p = 0.0004), mixed (r = -0.20, p = 0.0007) and non-calcified plaques (r = -0.18, p = 0.003). No correlation was seen with calcified plaques (r = -0.05, p = 0.39). In a fully adjusted multivariate model adiponectin levels remained predictive of total plaque burden (estimate: -0.036, 95%CI: -0.052 to -0.020, p<0.0001), mixed (estimate: -0.087, 95%CI: -0.132 to -0.042, p = 0.0001) and non-calcified plaques (estimate: -0.076, 95%CI: -0.115 to -0.038, p = 0.0001). Adiponectin levels were not associated with calcified plaques (estimate: -0.021, 95% CI: -0.043 to -0.001, p = 0.06). Since the majority of coronary plaques was calcified, adiponectin levels account for only 3% of the variability in total plaque number. In contrast, adiponectin accounts for approximately 20% of the variability in mixed and non-calcified plaque burden. CONCLUSIONS/SIGNIFICANCE: Adiponectin levels predict mixed and non-calcified coronary atherosclerotic plaque burden. Low adiponectin levels may contribute to coronary plaque vulnerability and may thus play a role in the pathophysiology of ACS.

Serum concentrations of cortisol, interleukin 6, leptin and adiponectin predict stress induced insulin resistance in acute inflammatory reactions.

INTRODUCTION: Inflammatory stimuli are causative for insulin resistance in obesity as well as in acute inflammatory reactions. Ongoing research has identified a variety of secreted proteins that are released from immune cells and adipocytes as mediators of insulin resistance; however, knowledge about their relevance for acute inflammatory insulin resistance remains limited. In this study we aimed for a clarification of the relevance of different insulin resistance mediating factors in an acute inflammatory situation. METHODS: Insulin resistance was measured in a cohort of 37 non-diabetic patients undergoing cardiac surgery by assessment of insulin requirement to maintain euglycaemia and repeated measurements of an insulin glycaemic index. The kinetics of cortisol, interleukin 6 (IL6), tumour necrosis factor alpha (TNFalpha), resistin, leptin and adiponectin were assessed by repeated measurements in a period of 48 h. RESULTS: Insulin resistance increased during the observation period and peaked 22 h after the beginning of the operation. IL6 and TNFalpha displayed an early increase with peak concentrations at the 4-h time point. Serum levels of cortisol, resistin and leptin increased more slowly and peaked at the 22-h time point, while adiponectin declined, reaching a base at the 22-h time point. Model assessment identified cortisol as the best predictor of insulin resistance, followed by IL6, leptin and adiponectin. No additional information was gained by modelling for TNFalpha, resistin, catecholamine infusion rate, sex, age, body mass index (BMI), operation time or medication. CONCLUSIONS: Serum cortisol levels are the best predictor for inflammatory insulin resistance followed by IL6, leptin and adiponectin. TNFalpha, and resistin have minor relevance as predictors of stress dependent insulin resistance.

Adipokines and insulin resistance.

Obesity is associated with an array of health problems in adult and pediatric populations. Understanding the pathogenesis of obesity and its metabolic sequelae has advanced rapidly over the past decades. Adipose tissue represents an active endocrine organ that, in addition to regulating fat mass and nutrient homeostasis, releases a large number of bioactive mediators (adipokines) that signal to organs of metabolic importance including brain, liver, skeletal muscle, and the immune system--thereby modulating hemostasis, blood pressure, lipid and glucose metabolism, inflammation, and atherosclerosis. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones adiponectin, chemerin, leptin, omentin, resistin, retinol binding protein 4, tumor necrosis factor-alpha and interleukin-6, vaspin, and visfatin on insulin resistance.

Resistin is an inflammatory marker of inflammatory bowel disease in humans.

OBJECTIVES: Resistin, a recently discovered adipokine, has been shown to be associated with inflammatory conditions such as insulin resistance, obesity, atherosclerosis and rheumatoid arthritis. We therefore hypothesized that (i) resistin levels may be elevated in patients with inflammatory bowel disease (IBD) and (ii) resistin levels may be associated with disease activity in IBD. METHODS: We addressed these questions by testing for associations between resistin plasma levels, inflammatory parameters and clinical disease activity in a case-control study with 235 patients with Crohn's disease (CD), 112 patients with ulcerative colitis (UC) and 144 healthy controls. RESULTS: Patients with IBD showed significantly higher resistin levels compared with controls (P<0.0001). In both, patients with CD and UC, resistin concentrations were significantly associated with elevated white blood cell count (P<0.0001), C-reactive protein (CRP) (P<0.0001) and disease activity (P< or =0.0001). In multivariate logistic regression analysis, resistin levels were identified as an independent predictor of active disease (odds ratio 1.014, 95% confidence interval 1.002-1.027, P=0.02) in patients with CD after adjusting for sex, age, body mass index, white blood cell count and CRP. In UC patients, resistin was associated with active disease in multivariate regression analysis after control for sex, age, body mass index and white blood cell count (odds ratio 1.015, 95% confidence interval 1.002-1.029, P=0.02). Addition of CRP, however, abolished this association. CONCLUSION: Resistin levels are an independent predictor of disease activity in patients with CD. Resistin may represent a novel link between inflammation and IBD.

Apolipoprotein A-IV is an independent predictor of disease activity in patients with inflammatory bowel disease.

BACKGROUND: ApoA-IV, an apolipoprotein (apo) with antioxidant, antiatherogenic, and antiinflammatory properties, was recently demonstrated to inhibit dextran sulfate sodium (DSS)-induced experimental colitis in mice. We therefore hypothesized that apoA-IV may be associated with disease activity in patients with inflammatory bowel disease (IBD). METHODS: We addressed this question by testing for associations between apoA-IV genotypes, apoA-IV plasma levels, inflammatory parameters, and clinical disease activity in 206 patients with Crohn's disease (CD), 95 subjects with ulcerative colitis (UC), and 157 healthy controls. RESULTS: In CD patients, apoA-IV plasma levels were inversely associated with C-reactive protein (CRP) (P = 0.005) and disease activity (P = 0.01) in univariate analysis. In multiple logistic regression analysis, apoA-IV levels were identified as an independent predictor of elevated CRP (odds ratio [OR] 0.956, 95% confidence interval [CI]: 0.916-0.998, P = 0.04) and active disease (OR 0.957, 95% CI: 0.918-0.998, P = 0.04). In UC patients the apoA-IV gene variant 360 His (P = 0.03) but not apoA-IV levels (P = 0.15) were associated with increased disease activity in univariate analysis. This association, however, was lost in multiple logistic regression analysis (OR 3.435, 95% CI 0.995-11.853, P = 0.05). CONCLUSIONS: To our knowledge, this is the first study to demonstrate an association of apoA-IV with disease activity in patients with CD. Further studies are needed to define the relationship of apoA-IV to IBD.

Endothelial lipase is less effective at influencing HDL metabolism in vivo in mice expressing apoA-II.

Endothelial lipase (EL) plays an important physiological role in modulating HDL metabolism. Data suggest that plasma contains an inhibitor of EL, and previous studies have suggested that apolipoprotein A-II (apoA-II) inhibits the activity of several enzymes involved in HDL metabolism. Therefore, we hypothesized that apoA-II may reduce the ability of EL to influence HDL metabolism. To test this hypothesis, we determined the effect of EL expression on plasma phospholipase activity and HDL metabolism in human apoA-I and human apoA-I/A-II transgenic mice. Expression of EL in vivo resulted in lower plasma phospholipase activity and significantly less reduction of HDL-cholesterol, phospholipid, and apoA-I levels in apoA-I/A-II double transgenic mice compared with apoA-I single transgenic mice. We conclude that the presence of apoA-II on HDL particles inhibits the ability of EL to influence the metabolism of HDL in vivo.

Dose-dependent acceleration of high-density lipoprotein catabolism by endothelial lipase.

BACKGROUND: Factors that regulate the metabolism of HDL and apolipoprotein A-I (apoA-I) are incompletely understood. Overexpression of endothelial lipase (EL) markedly reduces plasma levels of HDL cholesterol and apoA-I in mice, but the mechanisms of this effect remain unknown. METHODS AND RESULTS: We used different doses of a recombinant adenoviral vector to overexpress human EL in mice and studied the effects on plasma phospholipase activity, plasma lipids, HDL particle size, HDL turnover, and tissue sites of HDL degradation in mice. Overexpression of EL was associated with a significant dose-dependent increase in postheparin plasma phospholipase activity. Plasma phospholipid, HDL cholesterol, and apoA-I levels were markedly decreased, even at the lowest dose of vector. Kinetic studies demonstrated a significant dose-dependent increase in the fractional catabolic rate of HDL-apolipoprotein in EL-overexpressing mice. The postheparin plasma phospholipase activity was significantly positively correlated with HDL-apolipoprotein fractional catabolic rate. The uptake of apoA-I by the kidney and the liver was significantly increased by 2.5-fold and 3-fold, respectively, in mice overexpressing EL. CONCLUSIONS: Expression of EL in mice results in a dose-dependent increase in postheparin plasma phospholipase activity, catabolic rate of HDL-apolipoprotein, and uptake of apoA-I in both kidney and liver.

Effects of nonlipolytic ligand function of endothelial lipase on high density lipoprotein metabolism in vivo.

Endothelial lipase (EL) influences high density lipoprotein (HDL) metabolism in vivo and mediates bridging and uptake of HDL particles independent of its lipolytic activity in vitro. To determine whether EL has a nonlipolytic ligand function in HDL metabolism in vivo, 1 x 1011 particles of a recombinant adenovirus encoding human EL (AdEL), catalytically inactive human EL (AdELS149A), or control (Adnull) were injected into wild-type, apoA-I transgenic, and hepatic lipase knockout mice. ELS149A protein was expressed at higher levels than wild-type EL. EL and ELS149A protein were both substantially increased in the postheparin plasma compared with preheparin, indicating that both the wild-type and mutant EL were bound to cell-surface heparan sulfate proteoglycans. Overexpression of wild-type EL was associated with a significantly increased postheparin-plasma phospholipase activity and dramatically decreased levels of total cholesterol, HDL cholesterol, phospholipids, and apoA-I. Injection of AdELS149A did not result in increased phospholipase activity confirming that ELS149A was catalytically inactive. Expression of ELS149A did not decrease lipid or apoA-I levels in wild-type and apoA-I transgenic mice yet led to an intermediate reduction of total cholesterol, HDL cholesterol, and phospholipids in hepatic lipase-deficient mice compared with control and EL-expressing mice. Our study demonstrates for the first time that EL has both a lipolytic and nonlipolytic function in HDL metabolism in vivo. Lipolytic activity of EL, however, seems to be most important for its effects on systemic HDL metabolism.

Lipase H, a new member of the triglyceride lipase family synthesized by the intestine.

We report here the molecular cloning of a novel member of the triglyceride lipase family, a 2.4-kb cDNA encoding human lipase H (LIPH) and the mouse ortholog (Liph). The human LIPH cDNA encodes a 451-amino-acid protein with a lipase domain. Mouse Liph shows 85% amino acid identity and 75% nucleotide identity to human LIPH. Human LIPH exhibits 47% identity with phosphatidylserine-specific phospholipase A1 (PS-PLA1) and 46% identity with endothelial lipase (LIPG) and lipoprotein lipase (LPL). LIPH is localized on human chromosome 3q27-q28. Northern blot analysis revealed specific expression of LIPH mRNA in intestine, lung, and pancreas. Lipase H protein was also detected in human intestine. Lipase H is a secreted protein with an apparent molecular weight of 63 kDa. Although several lipid substrates were tested, the lipid substrate of LIPG was not identified. Like the other members of this gene family, LIPH may be involved in lipid and energy metabolism.