ABCG1 has a critical role in mediating cholesterol efflux to HDL and preventing cellular lipid accumulation.

Here we demonstrate that the ABC transporter ABCG1 plays a critical role in lipid homeostasis by controlling both tissue lipid levels and the efflux of cellular cholesterol to HDL. Targeted disruption of Abcg1 in mice has no effect on plasma lipids but results in massive accumulation of both neutral lipids and phospholipids in hepatocytes and in macrophages within multiple tissues following administration of a high-fat and -cholesterol diet. In contrast, overexpression of human ABCG1 protects murine tissues from dietary fat-induced lipid accumulation. Finally, we show that cholesterol efflux to HDL specifically requires ABCG1, whereas efflux to apoA1 requires ABCA1. These studies identify Abcg1 as a key gene involved in both cholesterol efflux to HDL and in tissue lipid homeostasis.

Accuracy and user performance evaluation of a blood glucose monitoring system which wirelessly transmits results to compatible insulin pumps.

Objective: To perform evaluations of the CONTOUR PLUS LINK 2.4 blood glucose monitoring system (BGMS) assessed according to ISO 15197:2013 criteria.Methods: Clinical trial registered at ClinicalTrials.gov (NCT01824355). In a laboratory study (Study 1), capillary fingertip blood samples from 100 subjects were evaluated in duplicate, using three test strip lots. In a clinical trial (Study 2), 113 adults with diabetes were enrolled, and BGMS results and Yellow Springs Instruments (YSI) analyzer reference measurements were compared for subject- and trial staff-obtained fingertip blood and subject-obtained palm blood. Subjects completed a questionnaire to evaluate BGMS ease of use.Results: In Study 1, 100% of combined results (all test strip lots) fulfilled ISO 15197:2013 section 6.3 criteria. In Study 2, 97.7% of subject-obtained fingertip results and 100% of trial staff-obtained fingertip results met ISO 15197:2013 section 8 criteria. Additionally, 93.8% of palm results were within ± 15 mg/dL of mean YSI measurements for glucose concentrations <100 mg/dL or ± 15% for glucose concentrations ≥100 mg/dL. Most subjects found the BGMS easy to use. There were three non-serious, non-device related adverse events.Conclusion: The BGMS exceeded minimum ISO 15197:2013-specified accuracy criteria in the laboratory and in the hands of lay users with diabetes.

Novel features of the rabbit transverse tubular system revealed by quantitative analysis of three-dimensional reconstructions from confocal images.

With scanning confocal microscopy we obtained three-dimensional (3D) reconstructions of the transverse tubular system (t-system) of rabbit ventricular cells. We accomplished this by labeling the t-system with dextran linked to fluorescein or, alternatively, wheat-germ agglutinin conjugated to an Alexa fluor dye. Image processing and visualization techniques allowed us to reconstruct the t-system in three dimensions. In a myocyte lying flat on a coverslip, t-tubules typically progressed from its upper and lower surfaces. 3D reconstructions of the t-tubules also suggested that some of them progressed from the sides of the cell. The analysis of single t-tubules revealed novel morphological features. The average diameter of single t-tubules from six cells was estimated to 448 +/- 172 nm (mean +/- SD, number of t-tubules 348, number of cross sections 5323). From reconstructions we were able to identify constrictions occurring every 1.87 +/- 1.09 microm along the principal axis of the tubule. The cross-sectional area of these constrictions was reduced to an average of 57.7 +/- 27.5% (number of constrictions 170) of the adjacent local maximal areas. Principal component analysis revealed flattening of t-tubular cross sections, confirming findings that we obtained from electron micrographs. Dextran- and wheat-germ agglutinin-associated signals were correlated in the t-system and are therefore equally good markers. The 3D structure of the t-system in rabbit ventricular myocytes seems to be less complex than that found in rat. Moreover, we found that t-tubules in rabbit have approximately twice the diameter of those in rat. We speculate that the constrictions (or regions between them) are sites of dyadic clefts and therefore can provide geometric markers for colocalizing dyadic proteins. In consideration of the resolution of the imaging system, we suggest that our methods permit us to obtain spatially resolved 3D reconstructions of the t-system in rabbit cells. We also propose that our methods allow us to characterize pathological defects of the t-system, e.g., its remodeling as a result of heart failure.

Oral small peptides render HDL antiinflammatory in mice and monkeys and reduce atherosclerosis in ApoE null mice.

A peptide containing only 4 amino acid residues (KRES) that is too small to form an amphipathic helix, reduced lipoprotein lipid hydroperoxides (LOOH), increased paraoxonase activity, increased plasma HDL-cholesterol levels, rendered HDL antiinflammatory, and reduced atherosclerosis in apoE null mice. KRES was orally effective when synthesized from either L or D-amino acids suggesting that peptide-protein interactions were not required. Remarkably, changing the order of 2 amino acids (from KRES to KERS) resulted in the loss of all biologic activity. Solubility in ethyl acetate and interaction with lipids, as determined by differential scanning calorimetry, indicated significant differences between KRES and KERS. Negative stain electron microscopy showed that KRES formed organized peptide-lipid structures whereas KERS did not. Another tetrapeptide FREL shared many of the physical-chemical properties of KRES and was biologically active in mice and monkeys when synthesized from either L- or D-amino acids. After oral administration KRES and FREL were found associated with HDL whereas KERS was not. We conclude that the ability of peptides to interact with lipids, remove LOOH and activate antioxidant enzymes associated with HDL determines their antiinflammatory and antiatherogenic properties regardless of their ability to form amphipathic helixes.

Impaired development of atherosclerosis in hyperlipidemic Ldlr-/- and ApoE-/- mice transplanted with Abcg1-/- bone marrow.

OBJECTIVE: The lungs of Abcg1-/- mice accumulate macrophage foam cells that contain high levels of unesterified and esterified cholesterol, consistent with a role for ABCG1 in facilitating the efflux of cholesterol from macrophages to high-density lipoprotein (HDL) and other exogenous sterol acceptors. Based on these observations, we investigated whether loss of ABCG1 affects foam cell deposition in the artery wall and the development of atherosclerosis. METHODS AND RESULTS: Bone marrow from wild-type or Abcg1-/- mice was transplanted into Ldlr-/- or ApoE-/- mice. After administration of a high-fat/high-cholesterol diet, plasma and tissue lipid levels and atherosclerotic lesion size were quantified and compared. Surprisingly, transplantation of Abcg1-/- bone marrow cells resulted in a significant reduction in lesion size in both mouse models, despite the fact that lipid levels increased in the lung, spleen, and kidney. Lesions of Ldlr-/- mice transplanted with Abcg1-/- cells contained increased numbers of apoptotic cells. Consistent with this observation, in vitro studies demonstrated that Abcg1-/- macrophages were more susceptible to oxidized low-density lipoprotein (ox-LDL)-dependent apoptosis than Abcg1+/+ cells. CONCLUSIONS: Diet-induced atherosclerosis is impaired when atherosclerotic-susceptible mice are transplanted with Abcg1-/- bone marrow. The demonstration that Abcg1-/- macrophages undergo accelerated apoptosis provides a mechanism to explain the decrease in the atherosclerotic lesions.

Functional adult myocardium in the absence of Na+-Ca2+ exchange: cardiac-specific knockout of NCX1.

The excitation-contraction coupling cycle in cardiac muscle is initiated by an influx of Ca2+ through voltage-dependent Ca2+ channels. Ca2+ influx induces a release of Ca2+ from the sarcoplasmic reticulum and myocyte contraction. To maintain Ca2+ homeostasis, Ca2+ entry is balanced by efflux mediated by the sarcolemmal Na+-Ca2+ exchanger. In the absence of Na+-Ca2+ exchange, it would be expected that cardiac myocytes would overload with Ca2+. Using Cre/loxP technology, we generated mice with a cardiac-specific knockout of the Na+-Ca2+ exchanger, NCX1. The exchanger is completely ablated in 80% to 90% of the cardiomyocytes as determined by immunoblot, immunofluorescence, and exchange function. Surprisingly, the NCX1 knockout mice live to adulthood with only modestly reduced cardiac function as assessed by echocardiography. At 7.5 weeks of age, measures of contractility are decreased by 20% to 30%. We detect no adaptation of the myocardium to the absence of the Na+-Ca2+ exchanger as measured by both immunoblots and microarray analysis. Ca2+ transients of isolated myocytes from knockout mice display normal magnitudes and relaxation kinetics and normal responses to isoproterenol. Under voltage clamp conditions, the current through L-type Ca2+ channels is reduced by 50%, although the number of channels is unchanged. An abbreviated action potential may further reduce Ca2+ influx. Rather than upregulate other Ca2+ efflux mechanisms, the myocardium appears to functionally adapt to the absence of the Na+-Ca2+ exchanger by limiting Ca2+ influx. The magnitude of Ca2+ transients appears to be maintained by an increased gain of sarcoplasmic reticular Ca2+ release. The myocardium of the NCX1 knockout mice undergoes a remarkable adaptation to maintain near normal cardiac function.

D-4F and statins synergize to render HDL antiinflammatory in mice and monkeys and cause lesion regression in old apolipoprotein E-null mice.

OBJECTIVE: We tested for synergy between pravastatin and D-4F by administering oral doses of each in combination that were predetermined to be ineffective when given as single agents. METHODS AND RESULTS: The combination significantly increased high-density lipoprotein (HDL)-cholesterol levels, apolipoprotein (apo)A-I levels, paraoxonase activity, rendered HDL antiinflammatory, prevented lesion formation in young (79% reduction in en face lesion area; P<0.0001) and caused regression of established lesions in old apoE null mice (ie, mice receiving the combination for 6 months had lesion areas that were smaller than those before the start of treatment (P=0.019 for en face lesion area; P=0.004 for aortic root sinus lesion area). After 6 months of treatment with the combination, en face lesion area was 38% of that in mice maintained on chow alone; P<0.00004) with a 22% reduction in macrophage content in the remaining lesions (P=0.001), indicating an overall reduction in macrophages of 79%. The combination increased intestinal apoA-I synthesis by 60% (P=0.011). In monkeys, the combination also rendered HDL antiinflammatory. CONCLUSIONS: These results suggest that the combination of a statin and an HDL-based therapy may be a particularly potent treatment strategy.

Outcomes of a Novel Training Program for Physician-Scientists: Integrating Graduate Degree Training With Specialty Fellowship.

BACKGROUND: Although physician-scientists generally contribute to the scientific enterprise by providing a breadth of knowledge complementary to that of other scientists, it is a challenge to recruit, train, and retain physicians in a research career pathway. OBJECTIVE: To assess the outcomes of a novel program that combines graduate coursework and research training with subspecialty fellowship. METHODS: A retrospective analysis was conducted of career outcomes for 123 physicians who graduated from the program during its first 20 years (1993-2013). Using curricula vitae, direct contact, and online confirmation, data were compiled on physicians' subsequent activities and careers as of 2013. Study outcomes included employment in academic and nonacademic research, academic clinical or private practice positions, and research grant funding. RESULTS: More than 80% of graduates were actively conducting research in academic, institutional, or industrial careers. The majority of graduates (71%) had academic appointments; a few (20%) were in private practice. Fifty percent had received career development awards, and 19% had received investigator-initiated National Institutes of Health (NIH) R01 or equivalent grants. Individuals who obtained a PhD during subspecialty training were significantly more likely to have major grant funding (NIH R series or equivalent) than those who obtained a Master of Science in Clinical Research. Trainees who obtained a PhD in a health services or health policy field were significantly more likely to have research appointments than those in basic science. CONCLUSIONS: Incorporation of graduate degree research, at the level of specialty or subspecialty clinical training, is a promising approach to training and retaining physician-scientists.

Oral D-4F causes formation of pre-beta high-density lipoprotein and improves high-density lipoprotein-mediated cholesterol efflux and reverse cholesterol transport from macrophages in apolipoprotein E-null mice.

BACKGROUND: These studies were designed to determine the mechanism of action of an oral apolipoprotein (apo) A-I mimetic peptide, D-4F, which previously was shown to dramatically reduce atherosclerosis in mice. METHODS AND RESULTS: Twenty minutes after 500 microg of D-4F was given orally to apoE-null mice, small cholesterol-containing particles (CCPs) of 7 to 8 nm with pre-beta mobility and enriched in apoA-I and paraoxonase activity were found in plasma. Before D-4F, both mature HDL and the fast protein liquid chromatography fractions containing the CCPs were proinflammatory. Twenty minutes after oral D-4F, HDL and CCPs became antiinflammatory, and there was an increase in HDL-mediated cholesterol efflux from macrophages in vitro. Oral D-4F also promoted reverse cholesterol transport from intraperitoneally injected cholesterol-loaded macrophages in vivo. In addition, oral D-4F significantly reduced lipoprotein lipid hydroperoxides (LOOH), except for pre-beta HDL fractions, in which LOOH increased. CONCLUSIONS: The mechanism of action of oral D-4F in apoE-null mice involves rapid formation of CCPs, with pre-beta mobility enriched in apoA-I and paraoxonase activity. As a result, lipoprotein LOOH are reduced, HDL becomes antiinflammatory, and HDL-mediated cholesterol efflux and reverse cholesterol transport from macrophages are stimulated.

Accuracy and user performance evaluation of a blood glucose monitoring system.

BACKGROUND: The accuracy of the Contour(®) Plus (Bayer HealthCare LLC, Diabetes Care, Whippany, NJ) blood glucose monitoring system (BGMS) was evaluated in two separate studies. MATERIALS AND METHODS: In the laboratory study, fingerstick samples from 100 subjects were tested in duplicate using three test strip lots and assessed per International Organization for Standardization (ISO) 15197:2003, Section 7 (≥95% of results within ±15 mg/dL or ±20% of the reference result for samples with glucose concentrations <75 and ≥75 mg/dL, respectively) and ISO 15197:2013, Section 6.3 (≥95% of results within ±15 mg/dL or ±15% of the reference result for samples with glucose concentrations <100 and ≥100 mg/dL, respectively) accuracy criteria. In the clinical trial, 220 subjects with diabetes, naive to the BGMS, tested capillary glucose from fingertip and palm blood samples and completed an ease-of-use questionnaire. BGMS and YSI glucose analyzer results were compared. RESULTS: In the laboratory study, 100% of results met ISO 15197:2003 and ISO 15197:2013 accuracy criteria. In the clinical trial, 100% and 99.1% of subject fingerstick results and 98.1% and 96.7% of subject palm results met ISO 15197:2003 and ISO 15197:2013 accuracy criteria, respectively. By Parkes Consensus Error Grid analysis, 100% of subject fingerstick results and 98.1% of subject palm results were within Zone A (remainder within Zone B). Questionnaire results showed most subjects found the BGMS easy to use. CONCLUSIONS: The Contour Plus BGMS meets ISO 15197:2003 and ISO 15197:2013 accuracy criteria in the laboratory and when used by untrained individuals.

Cardiac excitation-contraction coupling in the absence of Na(+) - Ca2+ exchange.

We investigate cardiac excitation-contraction coupling in the absence of sarcolemmal Na(+) - Ca(2+) exchange using NCX1 knock out mice. Knock out of NCX1 is embryonic lethal, and we measure Ca(2+) transients and contractions in heart tubes from embryos at day 9.5 post coitum. Immunoblot and electron microscopy both indicate that sarcoplasmic reticular membranes are diminished in the knock out (NCX(-/-)) heart tubes. Both Ni(2+) and nifedipine block excitation-contraction coupling in NCX-containing (NCX+) and NCX(-/-) heart tubes indicating an essential role for the L-type Ca(2+) current. Under basal conditions (1Hz stimulation), the NCX(-/-) heart tubes have normal Ca(2+) transients but are unable to maintain homeostasis when Ca(2+) fluxes are increased by various interventions (increased stimulation frequency, caffeine, isoproterenol). In each case, the NCX(-/-) heart tubes respond to the intervention in a more deleterious manner (increased diastolic Ca(2+), decreased Ca(2+) transient) than the NCX+ heart tubes. Expression of the sarcolemmal Ca(2+) pump was not upregulated. The sarcolemmal Ca(2+) pump, however, was able to compensate surprisingly well for the absence of Na(+) - Ca(2+) exchange under basal conditions.

Performance of the CONTOUR® TS Blood Glucose Monitoring System.

BACKGROUND: Self-monitoring of blood glucose (SMBG) remains an important component of diabetes management, engendering a need for affordable blood glucose (BG) meters that are accurate, precise, and convenient. The CONTOUR® TS is a BG meter that endeavors to meet this need. It uses glucose dehydrogenase/flavin dinucleotide chemistry, automatic test strip calibration, and autocompensation for hematocrit along with the ease of use that has come to be expected of a modern meter. The objective of this clinical trial was to determine whether the CONTOUR TS system met these criteria. METHODS: The system was evaluated at a single clinical site with 106 subjects with type 1 or type 2 diabetes. Blood glucose values ranged from 60 to 333 mg/dl over all subjects. Both lay users and health care professionals (HCPs) tested the meters, with test strips from three different lots. Results were compared to a reference analyzer of verified precision and accuracy. Forty-nine of the subjects also participated in a home study of the meter. Lay users learned to use the system without assistance and were surveyed on its use at the end of the study. RESULTS: When used with capillary blood, both subjects and HCPs obtained results that exceeded the International Organization for Standardization 15197:2003 criteria, (i.e., ≥95% of values fell within 20% or 15 mg/dl of the laboratory value for BG levels greater than or less than 75 mg/dl, respectively). Specifically, lay users achieved 97.9% and HCPs 98.6%. When used with venous blood, 99.8% of measurements were within the criteria. All measurements for both capillary and venous blood fell into zones A or B of the Parkes error grid, deemed clinically accurate. Hematocrit was found to have no influence on BG measurements. A large majority of the subjects found the system easy to learn and to use. CONCLUSIONS: The CONTOUR TS BG meter system gave accurate and reproducible results with both capillary and venous blood; subjects learned to use the meter system by following the user guide and quick reference guide.

Evaluation of an over-the-counter glycated hemoglobin (A1C) test kit.

BACKGROUND: Glycated hemoglobin (A1C) monitoring is an integral component of diabetes management. This study was conducted to evaluate the performance of the A1CNow® SELFCHECK device when used by lay users and health care professionals (HCPs) to measure A1C. METHODS: Subjects performed two A1CNow SELFCHECK finger-stick self-tests followed by a finger-stick test of the subject's blood by a HCP. The primary endpoint assessed accuracy of the subject and HCP A1CNow SELFCHECK readings. Secondary endpoints included precision, comprehension of instructional material (written material±DVD), and product satisfaction. For accuracy comparison, a venous blood sample was drawn from each subject and tested by laboratory (TOSOH) analysis. Subject comprehension of product instructional material was evaluated via first-time failure (FTF) rate as recorded by the HCP, and subject satisfaction was assessed through written survey. RESULTS: A total of 110 subjects with (n=93) and without (n=17) diabetes participated. Of 177 subject A1C values, 165 (93.2%) were within the acceptable range of ±13.5% of the laboratory reference value and considered accurate. Regression analysis showed good correlation of subject values to laboratory and HCP results (R2=0.93 for both). The average within-subject coefficient of variation was 4.57% (n=74). The FTF rates with and without instructional DVD were 11.3% (n=56) and 39.6% (n=54), respectively. Subjects with diabetes/prediabetes overwhelmingly indicated that they were "very" to "extremely" likely (93.5%) to discuss their home A1C results with their HCP. CONCLUSIONS: Lay users found the A1CNow SELFCHECK easy to use, and both lay users and HCPs were able to measure A1C accurately.

New bioactive bromotyrosine-derived alkaloid from a marine sponge Aplysinella sp.

A new bromotyrosine-derived alkaloid, (+)-aplysinillin (1), together with seven known compounds, was isolated from the crude organic extract of the marine sponge Aplysinella sp. collected from the Federated States of Micronesia. The structure of 1 was deduced by NMR and mass spectral techniques. Compounds 1-8 were evaluated for their inhibitory activity with the hyphae formation inhibition assay in Streptomyces 85E. Compounds 1 and 8 exhibited antiproliferative activities against the human breast adenocarcinoma cancer cell line MCF-7.

D-4F reduces EO6 immunoreactivity, SREBP-1c mRNA levels, and renal inflammation in LDL receptor-null mice fed a Western diet.

LDL receptor-null (LDLR(-/-)) mice on a Western diet (WD) develop endothelial dysfunction and atherosclerosis, which are improved by the apolipoprotein A-I (apoA-I) mimetic peptide D-4F. Focusing on the kidney, LDLR(-/-)mice were fed a WD with D-4F or the inactive control peptide scrambled D-4F (ScD-4F) added to their drinking water. The control mice (ScD-4F) developed glomerular changes, increased immunostaining for MCP-1/CCL2 chemokine, increased macrophage CD68 and F4/80 antigens, and increased oxidized phospholipids recognized by the EO6 monoclonal antibody in both glomerular and tublo-interstitial areas. All of these parameters were significantly reduced by D-4F treatment, approaching levels found in wild-type C57BL/6J or LDLR(-/-) mice fed a chow diet. Sterol-regulatory element binding protein-1c (SREBP-1c) mRNA levels and triglyceride levels were elevated in the kidneys of the control mice (ScD-4F) fed the WD compared with C57BL/6J and LDLR(-/-) mice on chow (P < 0.001 and P < 0.001, respectively) and compared with D-4F-treated mice on the WD (P < 0.01). There was no significant difference in plasma lipids, lipoproteins, glucose, blood pressure, or renal apoB levels between D-4F- and ScD-4F-treated mice. We conclude that D-4F reduced renal oxidized phospholipids, resulting in lower expression of SREBP-1c, which, in turn, resulted in lower triglyceride content and reduced renal inflammation.

Macromolecular transport in heart valves. III. Experiment and theory for the size distribution of extracellular liposomes in hyperlipidemic rabbits.

The heart valve leaflets of 29-day cholesterol-fed rabbits were examined by ultrarapid freezing without conventional chemical fixation/processing, followed by rotary shadow freeze-etching. This procedure images the leaflets' subendothelial extracellular matrix in extraordinary detail, and extracellular lipid liposomes, from 23 to 220 nm in diameter, clearly appear there. These liposomes are linked to matrix filaments and appear in clusters. Their size distribution shows 60.7% with diameters 23-69 nm, 31.7% between 70 and 119 nm, 7.3% between 120 and 169 nm, and 0.3% between 170 and 220 nm (superlarge) and suggests that smaller liposomes can fuse into larger ones. We couple our model from Part II of this series (Zeng Z, Yin Y, Jan KM, Rumschitzki DS. Am J Physiol Heart Circ Physiol 292: H2671-H2686, 2007) for lipid transport into the leaflet to the nucleation-polymerization model hierarchy for liposome formation proposed originally for aortic liposomes to predict liposome formation/growth in heart valves. Simulations show that the simplest such model cannot account for the observed size distribution. However, modifying this model by including liposome fusing/merging, using parameters determined from aortic liposomes, leads to predicted size distributions in excellent agreement with our valve data. Evolutions of both the liposome size distribution and total liposome mass suggest that fusing becomes significant only after 2 wk of high lumen cholesterol. Inclusion of phagocytosis by macrophages limits the otherwise monotonically increasing total liposome mass, while keeping the excellent fit of the liposome size distribution to the data.

Deletion of the transmembrane transporter ABCG1 results in progressive pulmonary lipidosis.

We show that mice lacking the ATP-binding cassette transmembrane transporter ABCG1 show progressive and age-dependent severe pulmonary lipidosis that recapitulates the phenotypes of different respiratory syndromes in both humans and mice. The lungs of chow-fed Abcg1(-/-) mice, >6-months old, exhibit extensive subpleural cellular accumulation, macrophage, and pneumocyte type 2 hypertrophy, massive lipid deposition in both macrophages and pneumocytes and increased levels of surfactant. No such abnormalities are observed at 3 months of age. However, gene expression profiling reveals significant changes in the levels of mRNAs encoding key genes involved in lipid metabolism in both 3- and 8-month-old Abcg1(-/-) mice. These data suggest that the lungs of young Abcg1(-/-) mice maintain normal lipid levels by repressing lipid biosynthetic pathways and that such compensation is inadequate as the mice mature. Studies with A-549 cells, a model for pneumocytes type 2, demonstrate that overexpression of ABCG1 specifically stimulates the efflux of cellular cholesterol by a process that is dependent upon phospholipid secretion. In addition, we demonstrate that Abcg1(-/-), but not wild-type macrophages, accumulate cholesterol ester droplets when incubated with surfactant. Together, these data provide a mechanism to explain the lipid accumulation in the lungs of Abcg1(-/-)mice. In summary, our results demonstrate that ABCG1 plays essential roles in pulmonary lipid homeostasis.

D-4F decreases brain arteriole inflammation and improves cognitive performance in LDL receptor-null mice on a Western diet.

LDL receptor-null mice on a Western diet (WD) have inflammation in large arteries and endothelial dysfunction in small arteries, which are improved with the apolipoprotein A-I mimetic D-4F. The role of hyperlipidemia in causing inflammation of very small vessels such as brain arterioles has not previously been studied. A WD caused a marked increase in the percent of brain arterioles with associated macrophages (microglia) (P < 0.01), which was reduced by oral D-4F but not by scrambled D-4F (ScD-4F; P < 0.01). D-4F (but not ScD-4F) reduced the percent of brain arterioles associated with CCL3/macrophage inflammatory protein-1alpha (P < 0.01) and CCL2/monocyte chemoattractant protein-1 (P < 0.001). A WD increased (P < 0.001) brain arteriole wall thickness and smooth muscle alpha-actin, which was reduced by D-4F but not by ScD-4F (P < 0.0001). There was no difference in plasma lipid levels, blood pressure, or arteriole lumen diameter with D-4F treatment. Cognitive performance in the T-maze continuous alternation task and in the Morris Water Maze was impaired by a WD and was significantly improved with D-4F but not ScD-4F (P < 0.05). We conclude that a WD induces brain arteriole inflammation and cognitive impairment that is ameliorated by oral D-4F without altering plasma lipids, blood pressure, or arteriole lumen size.

Lipid retention in the arterial wall of two mouse strains with different atherosclerosis susceptibility.

LDL deposition in the subendothelium of arterial walls is the initial event in the development of atherosclerosis. The deposited LDL undergoes oxidative modification by arterial wall cells to become oxidized LDL and consequently contributes to atherosclerotic formation. Using mouse strains C57BL/6J (B6) and C3H/HeJ (C3H), which differ markedly in susceptibility to atherosclerosis, we determined whether variation in subendothelial retention of apolipoprotein B (apoB)-containing lipoproteins constitutes a genetic component in atherosclerosis. Lipoprotein retention was quantitated by Western blot analysis to detect the presence of apoB in aortic walls before foam cells developed. In both dietary and apoE-deficient models, B6 mice exhibited up to a 2-fold increase of apoB in the aortic wall compared with C3H mice. This increase could not be attributed to differences in plasma lipid levels of the two strains. In vitro, endothelial cells from C3H mice took up more acetylated and oxidized LDL but not native LDL and converted more native LDL to oxidized LDL than did endothelial cells from B6 mice. C3H mice expressed more scavenger receptor A in their aortic wall than B6 mice. Thus, variation in the subendothelial retention of apoB-containing lipoproteins cannot explain the dramatic difference in atherosclerosis susceptibility between B6 and C3H mice, and endothelial cells may play a role in alleviating lipid accumulation in arterial walls.