Effects of niacin and omega-3 fatty acids on HDL-apolipoprotein A-I exchange in subjects with metabolic syndrome

HDL-apolipoprotein A-I exchange (HAE) measures a functional property associated with HDL's ability to mediate reverse cholesterol transport. HAE has been used to examine HDL function in case-control studies but not in studies of therapeutics that alter HDL particle composition. This study investigates whether niacin and omega-3 fatty acids induce measurable changes in HAE using a cohort of fifty-six subjects with metabolic syndrome (MetS) who were previously recruited to a double-blind trial where they were randomized to 16 weeks of treatment with dual placebo, extended-release niacin (ERN, 2g/day), prescription omega-3 ethyl esters (P-OM3, 4g/day), or the combination. HAE was assessed at the beginning and end of the study. Compared to placebo, ERN and P-OM3 alone significantly increased HAE by 15.1% [8.2, 22.0] (P<0.0001) and 11.1% [4.5, 17.7] (P<0.0005), respectively, while in combination they increased HAE by 10.0% [2.5, 15.8] (P = 0.005). When HAE was evaluated per unit mass of apoA-I ERN increased apoA-I specific exchange activity by 20% (2, 41 CI, P = 0.02) and P-OM3 by 28% (9.6, 48 CI, P<0.0006). However the combination had no statistically significant effect, 10% (-9, 31 CI, P = 0.39). With regard to P-OM3 therapy in particular, the HAE assay detected an increase in this property in the absence of a concomitant rise in HDL-C and apoA-I levels, suggesting that the assay can detect functional changes in HDL that occur in the absence of traditional biomarkers.

Meta-analysis of the effect of colchicine on C-reactive protein in patients with acute and chronic coronary syndromes

OBJECTIVE

The anti-inflammatory drug colchicine has recently shown benefits in the prevention of major adverse cardiovascular events (MACE) in patients with the acute coronary syndrome (ACS) and chronic coronary syndromes (CCS). This meta-analysis focuses on understanding Colchicine's effects on the high-sensitivity C-reactive protein (hs-CRP) to provide mechanistic insight to explain its clinical event reduction.

METHODS

A computerized search of MEDLINE was conducted to retrieve journal articles with studies performed on humans from 1 January 2005 to 1 January 2022, using keywords: 'Colchicine AND Coronary', 'Colchicine AND CRP', and 'Colchicine AND Coronary Artery Disease'. Studies were included if they measured hs-CRP changes from baseline, and colchicine or placebo were given to patients with ACS or CCS.

RESULTS

Thirteen studies with a biomarker subgroup population of 1636 patients were included in the hs-CRP meta-analysis. Of those 13 studies, 8 studies with a total population of 6016 reported clinical events defined as myocardial infarction (MI), stroke, cardiovascular death, periprocedural MI, repeat angina after PCI and repeat revascularization. Multivariate analysis revealed a weak negative correlation of -0.1056 ( P  = 0.805) between change in CRP and clinical events. Overall, colchicine treatment resulted in a greater reduction in hs-CRP levels compared with placebo (Mean Difference: -1.59; 95% Confidence Interval, -2.40 to -0.79, P = 0.0001) and clinical events (Odds Ratio: 0.78; 95% Confidence Interval 0.64 to 0.95, P = 0.01).

CONCLUSION

Colchicine therapy is associated with a reduction in hs-CRP and clinical events in patients with ACS and CCS. This finding supports colchicine's anti-inflammatory efficacy via CRP reduction to explain its clinical benefit.

Recording and analysis of slow waves of the small intestine of mice with heart failure

BACKGROUND

Gastrointestinal (GI) symptoms in heart failure (HF) patients are associated with increased morbidity and mortality. We hypothesized that HF reduces bioelectrical activity underlying peristalsis. In this study, we aimed to establish a method to capture and analyze slow waves (SW) in the small intestine in mice with HF.

METHODS

We established a model of HF secondary to coronary artery disease in mice overexpressing tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells. The myoelectric activity was recorded from the small intestine in live animals under anesthesia. The low- and high-frequency components of SW were isolated in MATLAB and compared between the control (n = 12) and eTNAP groups (n = 8). C-kit-positive interstitial cells of Cajal (ICC) and Pgp9.5-positive myenteric neurons were detected by immunofluorescence. Myenteric ganglia were assessed by hematoxylin and eosin (H&E) staining.

RESULTS

SW activity was successfully captured in vivo, with both high- and low-frequency components. Low-frequency component of SW was not different between endothelial TNAP (eTNAP) and control mice (mean[95% CI]: 0.032[0.025-0.039] vs. 0.040[0.028-0.052]). High-frequency component of SW showed a reduction eTNAP mice relative to controls (0.221[0.140-0.302] vs. 0.394[0.295-0.489], p < 0.01). Dysrhythmia was also apparent upon visual review of signals. The density of ICC and neuronal networks remained the same between the two groups. No significant reduction in the size of myenteric ganglia of eTNAP mice was observed.

CONCLUSIONS

A method to acquire SW activity from small intestines in vivo and isolate low- and high-frequency components was established. The results indicate that HF might be associated with reduced high-frequency SW activity.

Paradoxical reduction of plasma lipids and atherosclerosis in mice with adenine-induced chronic kidney disease and hypercholesterolemia

Background

Atherosclerotic cardiovascular disease is prevalent among patients with chronic kidney disease (CKD). In this study, we initially aimed to test whether vascular calcification associated with CKD can worsen atherosclerosis. However, a paradoxical finding emerged from attempting to test this hypothesis in a mouse model of adenine-induced CKD.

Methods

We combined adenine-induced CKD and diet-induced atherosclerosis in mice with a mutation in the low-density lipoprotein receptor gene. In the first study, mice were co-treated with 0.2% adenine in a western diet for 8 weeks to induce CKD and atherosclerosis simultaneously. In the second study, mice were pre-treated with adenine in a regular diet for 8 weeks, followed by a western diet for another 8 weeks.

Results

Co-treatment with adenine and a western diet resulted in a reduction of plasma triglycerides and cholesterol, liver lipid contents, and atherosclerosis in co-treated mice when compared with the western-only group, despite a fully penetrant CKD phenotype developed in response to adenine. In the two-step model, renal tubulointerstitial damage and polyuria persisted after the discontinuation of adenine in the adenine-pre-treated mice. The mice, however, had similar plasma triglycerides, cholesterol, liver lipid contents, and aortic root atherosclerosis after being fed a western diet, irrespective of adenine pre-treatment. Unexpectedly, adenine pre-treated mice consumed twice the calories from the diet as those not pre-treated without showing an increase in body weight.

Conclusion

The adenine-induced CKD model does not recapitulate accelerated atherosclerosis, limiting its use in pre-clinical studies. The results indicate that excessive adenine intake impacts lipid metabolism.

Vitamin K antagonists and cardiovascular calcification: A systematic review and meta-analysis

Background

Many patients treated with Vitamin K antagonists (VKA) for anticoagulation have concomitant vascular or valvular calcification. This meta-analysis aimed to evaluate a hypothesis that vascular and valvular calcification is a side-effect of VKA treatment.

Methods

We conducted a systematic literature search to identify studies that reported vascular or valvular calcification in patients treated with VKA. The associations between VKA use and calcification were analyzed with random-effects inverse variance models and reported as odds ratios (OR) and 95% confidence intervals (95% CI). In addition, univariate meta-regression analyses were utilized to identify any effect moderators.

Results

Thirty-five studies were included (45,757 patients; 6,251 VKA users). The median follow-up was 2.3 years [interquartile range (IQR) of 1.2–4.0]; age 66.2 ± 3.6 years (mean ± SD); the majority of participants were males [77% (IQR: 72–95%)]. VKA use was associated with an increased OR for coronary artery calcification [1.21 (1.08, 1.36), p = 0.001], moderated by the duration of treatment [meta-regression coefficient B of 0.08 (0.03, 0.13), p = 0.0005]. Extra-coronary calcification affecting the aorta, carotid artery, breast artery, and arteries of lower extremities, was also increased in VKA treated patients [1.86 (1.43, 2.42), p < 0.00001] and moderated by the author-reported statistical adjustments of the effect estimates [B: −0.63 (−1.19, −0.08), p = 0.016]. The effect of VKA on the aortic valve calcification was significant [3.07 (1.90, 4.96), p < 0.00001]; however, these studies suffered from a high risk of publication bias.

Conclusion

Vascular and valvular calcification are potential side effects of VKA. The clinical significance of these side effects on cardiovascular outcomes deserves further investigation.

Addressing disparities in medicine through medical curriculum change: a student perspective

Cultural competency training has been a focus of medical schools for some time. An essential step in developing culturally competent physicians, effective cultural competency training has previously been researched at medical schools. Before forming a diversity task force to head cultural competency training, one medical school utilized medical student volunteers to review current teaching material and provide suggestions to increase cultural competency training. A study group consisting of three faculty members and 29 medical students was formed on a voluntary basis during the summer of 2020. Based on medical student opinion and reviewed teaching materials, learning tools were created to guide medical curricular updates. This experience resulted in the formation of four teaching tools: a didactic lecture checklist to include more diverse patient populations; case-based learning objectives that focus on social determinants of health; a facilitator question script to encourage group discussion and student feedback on the given clinical cases; and a student reflection form on the effects of race, gender, and socioeconomic status on patients and medical professionals in the clinical setting. Updating the medical school curriculum is a constant and ongoing process. Forming a diversity task force to guide these changes and regularly review medical teaching materials will help train physicians ready to care for a diverse patient population. In addition, the use of the suggested teaching tools may help guide the review process for such committees at other medical schools.

Long-term consumption of artificial sweeteners does not affect cardiovascular health and survival in rats

Background

Recent epidemiological cohort studies have suggested that consumption of artificial sweeteners (AS) is associated with adverse cardiovascular events and mortality. However, these population association studies cannot establish a causal relationship. In this study we investigated the effect of long-term (1-year) consumption of AS (Equal and Splenda, two commonly used AS) on cardiovascular health and survival in rats.

Methods

Adult Sprague-Dawley rats (both sexes, 4-5 months old) were randomized into the following 3 groups: control (n = 21), AS Equal (n = 21) and Splenda (n = 18). In the AS groups, Equal or Splenda was added to the drinking water (2-packets/250 ml), while drinking water alone was used in the control rats. The treatment was administered for 12 months. Cardiovascular function and survival were monitored in all animals.

Results

It was found that rats in the AS groups consistently consumed more sweetened water than those in the control group. AS did not affect body weight, non-fasting blood cholesterol, triglycerides, blood pressure or pulse wave velocity. There were no significant differences in left ventricular wall thicknesses, chamber dimension, cardiac function or survival. AS did not affect heart rate or atrial effective refractory period. However, rats in both Equal and Splenda groups had prolonged PR intervals (63 ± 5ms in Equal, 68 ± 6 ms in Splenda, vs 56 ± 8 ms in control, p < 0.05) and a tendency of increased atrial fibrillation inducibility.

Conclusion

Long-term consumption of AS does not affect cardiovascular structure, function or survival but may cause some electrophysiological abnormalities with prolonged PR intervals and a tendency of increased atrial fibrillation inducibility in rats.

Abstract P123: Effects Of Lipid Control On Coronary Calcification

Introduction: Lipid lowering drugs are some of the most prescribed medications to control coronary artery disease (CAD). The long-term lipid lowering effects on coronary artery calcium (CAC) progression remain a subject of controversy with inconclusive results from multiple literature reviews. The purpose of this meta-analysis is to elucidate the relationship between lipid control and CAC progression.

Methods: A computerized search of MEDLINE was conducted using the search terms “coronary”, “calcification”, “statin”, and “lipid lowering.” Search filters included studies in English performed on human subjects, clinical trials, and journal articles. Studies were included if they measured mean value changes from baseline in coronary calcium using cardiac computed tomography. Data were extracted from the articles according to the Cochrane manual. RevMan 5.4 was used to aggregate the studies and report statistics.

Results: A total of 13 studies were included with a total of 6671 patients. LDL reduction amongst the studies was significant as compared to placebo or lower dose lipid lowering therapy (standardized mean difference [SMD]: -0.71; 95% CI: -0.79, -0.64; p<0.00001). Study heterogeneity was not significant amongst the CAC progression studies (p=0.19). An increase in CAC was statistically significant (standardized mean difference [SMD]: 0.10; 95% CI: 0.02, 0.17; p=0.009).

Conclusion: Lipid lowering therapy shows efficacy in LDL reduction however, it does not lead to coronary calcium reduction. Further studies are needed to elucidate the long-term effects of lipid powering on CAC and the prognostic value of CAC in CAD parents receiving optimal therapy.

Abstract P128: Reducing Inflammation In Coronary Atherosclerosis: A Renewed Look At Colchicine

Introduction: Atherosclerosis is an inflammatory disease. Randomized controlled trials (RCT) have demonstrated that targeting inflammation is important for the secondary prevention of major adverse cardiovascular events (MACE) in patients with acute coronary syndrome (ACS) and chronic coronary artery disease (CAD). Out of these trials, low-dose colchicine has emerged as an inexpensive therapy for coronary atherosclerosis. This meta-analysis focuses to understand colchicine’s anti-inflammatory efficacy via reduction in high sensitivity C-Reactive Protein (hs-CRP) in patients with ACS and CAD.

Methods: A computerized search of MEDLINE was conducted to retrieve journal articles reporting the results in human studies performed from January 1, 2005 to January 1, 2021 using the keywords: “Colchicine” AND “Coronary” OR “CRP” OR “Coronary Artery Disease.” Studies were included if they measured hs-CRP changes from baseline and colchicine or placebo were given to patients with ACS or CAD. Studies were graded on quality via the Jadad scoring criteria.

Results: A total of nine studies with a total population of 1502 patients and mean Jadad score of 4 were included in the meta-analysis. Five studies were RCT. The mean/median age ranged from 57 to 67 years while the duration of therapy ranged from one day to one year. Overall, colchicine treatment reduced hs-CRP levels compared with placebo (standardized mean difference [SMD]: -0.45; 95% CI: -0.68, -0.22; p=0.0001).

Conclusion: Colchicine reduces hs-CRP in patients with ACS and CAD. This finding supports the role of colchicine in the reduction of inflammation associated with ACS or CAD. Further randomized control trials are needed to quantify long-term inflammatory control and subsequent MACE reduction.

Abstract P129: Ablation Of TNAP (tissue-nonspecific Alkaline Phosphatase) In Macrophages Does Not Affect Atherosclerotic Plaque Calcification Or Cardiovascular Physiology

Introduction: Increased expression of TNAP (tissue-nonspecific alkaline phosphatase) in macrophages exacerbates atherosclerotic calcification in a mouse model. However, whether or not TNAP is necessary in the progression of calcification, or for proper cardiac function has yet been studied.

Objective: The purpose of this study was to test the effect of TNAP ablation in macrophages on atherosclerotic plaque calcification and cardiovascular physiology, and compare it to a wild type situation.

Methods: Macrophage-specific WHC-mTNAP knockout (KO) mice were produced in our colony by intercrossing floxed alpl transgenic mice ( alpl gene encodes TNAP) and macrophage-specific CRE recombinase mice, in which CRE was expressed under the control of the lysozyme gene promoter. The macrophage TNAP KO strain was developed on the background of homozygous WHC (“wicked high cholesterol”) mutation in the low density lipoprotein receptor gene. WHC-TNAP KO (n=10) and their WHC littermates (n=9) were placed on an atherosclerosis inducing diet at 8 weeks of age. The mice were maintained on the diet for 44 weeks, or until they turned 52 weeks. Microcomputed tomography (microCT) analyses of calcification in the aortic roots and arches were performed ex vivo . Echocardiographic studies were performed to assess cardiac structure and function at 52 weeks of age. Data were analyzed via a 2-way ANOVA to calculate the effect of TNAP ablation on calcification and cardiovascular physiology while adjusting for sex.

Results: CT data showed no significant difference in calcification levels between the two genotypes. Cardiac parameters such as left ventricular (LV) mass, LV diameter and wall thickness, ejection fraction, fractional shortening and cardiac output also showed no signifgant difference between the two genotypes.

Conclusion: Our data suggest that, despite TNAP expression in macrophages being sufficient to induce calcification of atherosclerotic plaques, it is not necessary in the calcification process. To the extent of our study, the ablation of TNAP in macrophages does not appear to have any consequences in a mouse model of atherosclerosis.

Abstract P161: Novel Micro-CT Method To Assess Atherosclerotic Calcification In Mice

Introduction: Animal models are used to study mechanisms and consequences of calcification in atherosclerosis. As a standard practice, vascular calcification in a mouse model is measured by laborious histological preparation and calcium staining. In this study, we developed an ex-vivo micro-CT (μCT) method to quantify calcium volume in the aortic roots and arches in mice with atherosclerosis.

Objective: The purpose of this study was to evaluate feasibility and compare calcium measurements between the μCT and histological methods.

Methods: We used a mouse model of increased atherosclerotic calcification due to overexpression of tissue nonspecific alkaline phosphatase (TNAP) in macrophages. Formalin-fixed tissues were dissected and slowly immersed in mineral oil. Samples were assembled in cryogenic vials pre-filled with mineral oil. Cotton was used to immobilize and space the samples. μCT images of whole hearts and aortic arches were collected at a 7.1 micron resolution. Multiple Deep Learning models, implemented in Dragonfly 2020.1 (ORS), were trained on one sample for image segmentation. Histological analysis was performed according to standard protocols.

Results: Multiple preparations of hearts and aortic roots can be scanned in a single overnight experiment. A Deep Learning model of the U-Net5 architecture was most successful in the segmentation of soft tissues and calcifications, while excluding μCT artifacts. The data showed a good correlation between detection of calcium by μCT and histology. μCT analysis of samples from 1-year-old TNAP transgenic mice demonstrated a 4-fold increase in calcification volume compared to control mice.

Conclusion: Our μCT method is feasible and, in some aspects, superior to the traditional histological analysis because it is less time-consuming and less prone to artifacts. μCT approach is non-destructive thus permitting analyses of samples by multiple analytical methods after removal of mineral oil.

Effects of inflammation and soluble epoxide hydrolase inhibition on oxylipin composition of very low-density lipoproteins in isolated perfused rat livers

Oxylipins are metabolites of polyunsaturated fatty acids that mediate cardiovascular health by attenuation of inflammation, vascular tone, hemostasis, and thrombosis. Very low-density lipoproteins (VLDL) contain oxylipins, but it is unknown whether the liver regulates their concentrations. In this study, we used a perfused liver model to observe the effect of inflammatory lipopolysaccharide (LPS) challenge and soluble epoxide hydrolase inhibition (sEHi) on VLDL oxylipins. A compartmental model of deuterium-labeled linoleic acid and palmitic acid incorporation into VLDL was also developed to assess the dependence of VLDL oxylipins on fatty acid incorporation rates. LPS decreased the total fatty acid VLDL content by 30% [6%,47%], and decreased final concentration of several oxylipins by a similar amount (13-HOTrE, 35% [4%,55%], -1.3 nM; 9(10)-EpODE, 29% [3%,49%], -2.0 nM; 15(16)-EpODE, 29% [2%,49%], -1.6 nM; AA-derived diols, 32% [5%,52%], -2.4 nM; 19(20)-DiHDPA, 31% [7%,50%], -1.0 nM). However, the EPA-derived epoxide, 17(18)-EpETE, was decreased by 75% [49%,88%], (-0.52 nM) with LPS, double the suppression of other oxylipins. sEHi increased final concentration of DHA epoxide, 16(17)-EpDPE, by 99% [35%,193%], (2.0 nM). Final VLDL-oxylipin concentrations with LPS treatment were not correlated with linoleic acid kinetics, suggesting they were independently regulated under inflammatory conditions. We conclude that the liver regulates oxylipin incorporation into VLDL, and the oxylipin content is altered by LPS challenge and by inhibition of the epoxide hydrolase pathway. This provides evidence for delivery of systemic oxylipin signals by VLDL transport.

Trafficking of nonesterified fatty acids in insulin resistance and relationship to dysglycemia

In adipose, insulin functions to suppress intracellular lipolysis and secretion of nonesterified fatty acid (NEFA) into plasma. We applied glucose and NEFA minimal models (MM) following a frequently sampled intravenous glucose tolerance test (FSIVGTT) to assess glucose-specific and NEFA-specific insulin resistance. We used total NEFA and individual fatty acids in the NEFA MM, comparing the model parameters in metabolic syndrome (MetSyn) subjects (n = 52) with optimally healthy controls (OptHC; n = 14). Results are reported as mean difference (95% confidence interval). Using the glucose MM, MetSyn subjects had lower [-73% (-82, -57)] sensitivity to insulin (S_i) and higher [138% (44, 293)] acute insulin response to glucose (AIR_g). Using the NEFA MM, MetSyn subjects had lower [-24% (-35, -13)] percent suppression, higher [32% (15, 52)] threshold glucose (g_s), and a higher [81% (12, 192)] affinity constant altering NEFA secretion (ϕ). Comparing fatty acids, percent suppression was lower in myristic acid (MA) than in all other fatty acids, and the stearic acid (SA) response was so unique that it did not fit the NEFA MM. MA and SA percent of total were increased at 50 min after glucose injection, whereas oleic acid (OA) and palmitic acid (PA) were decreased (P < 0.05). We conclude that the NEFA MM, as well as the response of individual NEFA fatty acids after a FSIVGTT, differ between OptHC and MetSyn subjects and that the NEFA MM parameters differ between individual fatty acids.

Homoarginine Supplementation Prevents Left Ventricular Dilatation and Preserves Systolic Function in a Model of Coronary Artery Disease

Background

Homoarginine (hArg) has been shown to be cardioprotective in a model of ischemic heart failure; however, the mechanism remains unknown. hArg can inhibit tissue‐nonspecific alkaline phosphatase (TNAP), an enzyme that promotes vascular calcification. We hypothesized that hArg will exert beneficial effects by reducing calcification in a mouse model of coronary artery disease associated with TNAP overexpression and hypercholesterolemia.

Methods and Results

TNAP was overexpressed in the endothelium in mice homozygous for a low‐density lipoprotein receptor mutation (wicked high cholesterol [WHC] allele). WHC and WHC–endothelial TNAP mice received placebo or hArg supplementation (14 mg/L in drinking water) starting at 6 weeks of age simultaneously with an atherogenic diet. Outcomes were compared between the groups after 4 to 5 weeks on treatment. Experiments were performed in males, which presented a study limitation. As expected, WHC–endothelial TNAP mice on the placebo had increased mortality (median survival 27 days, P<0.0001), increased coronary calcium and lipids (P<0.01), increased left ventricular end‐diastolic diameter (P<0.0001), reduced ejection fraction (P<0.05), and increased myocardial fibrosis (P<0.0001) compared with WHC mice. Contrary to our hypothesis, hArg neither inhibited TNAP activity in vivo nor reduced coronary artery calcification and atherosclerosis in WHC–endothelial TNAP mice; however, compared with the placebo, hArg prevented left ventricular dilatation (P<0.01), preserved ejection fraction (P<0.05), and reduced myocardial fibrosis (P<0.001).

Conclusions

The beneficial effect of hArg supplementation in the setting of calcified coronary artery disease is likely due to its direct protective actions on the myocardial response to the ischemic injury and not to the inhibition of TNAP activity and calcification.

Triiodothyronine Reduces Vascular Dysfunction Associated with Hypertension by Attenuating Protein Kinase G/Vasodilator-Stimulated Phosphoprotein Signaling

Vascular dysfunction associated with hypertension comprises hypercontractility and impaired vasodilation. We have previously demonstrated that triiodothyronine (T3), the active form of thyroid hormone, has vasodilatory effects acting through rapid onset mechanisms. In the present study, we examined whether T3 mitigates vascular dysfunction associated with hypertension. To test the direct effects of T3 in hypertensive vessels, aortas from female Dahl salt-sensitive (Dahl SS) rats fed a high-salt diet (8% NaCl, HS group) and their age-matched controls fed a standard low-salt diet (0.3% NaCl, LS group) for 16 weeks were isolated and used in ex vivo vascular reactivity studies. We confirmed that the HS group exhibited a higher systolic blood pressure in comparison with the control LS group and displayed aortic remodeling. Aortas from both groups were pretreated with T3 (0.1 μM) for 30 minutes at 37°C in a 5% CO₂ incubator before functional vascular studies. T3 treatment significantly attenuated hypercontractility and improved impaired endothelium-dependent vasodilation in aortas from the HS group. These vascular improvements in response to T3 were accompanied by increased phosphorylation of vasodilator-stimulated phosphoprotein (VASP) at serine 239, a vasodilatory factor of the cGMP-dependent protein kinase (PKG)/VASP signaling pathway in vascular smooth muscle cells. Moreover, increased production of reactive oxygen species in aortas from the HS group were significantly reduced by T3, suggesting a potential antioxidant effect of T3 in the vasculature. These results demonstrate that T3 can mitigate hypertension-related vascular dysfunction through the VASP signaling pathway and by reducing vascular ROS production. SIGNIFICANCE STATEMENT: This study demonstrates that triiodothyronine (T3) directly acts on vascular tone and has a beneficial effect in hypertension-induced vascular dysfunction. T3 augmented vasodilation and diminished vasoconstriction in blood vessels from hypertensive rats in association with activation of the protein kinase G/vasodilator-stimulated phosphoprotein signaling pathway that activates vascular relaxation and exerted an antioxidant effect. Collectively, these results show that T3 is a potential vasoprotective agent with rapid action on hypertension-related vascular dysfunction.

Malformation of the Posterior Cerebellar Vermis Is a Common Neuroanatomical Phenotype of Genetically Engineered Mice on the C57BL/6 Background

C57BL/6 mice exhibit spontaneous cerebellar malformations consisting of heterotopic neurons and glia in the molecular layer of the posterior vermis, indicative of neuronal migration defect during cerebellar development. Recognizing that many genetically engineered (GE) mouse lines are produced from C57BL/6 ES cells or backcrossed to this strain, we performed histological analyses and found that cerebellar heterotopia were a common feature present in the majority of GE lines on this background. Furthermore, we identify GE mouse lines that will be valuable in the study of cerebellar malformations including diverse driver, reporter, and optogenetic lines. Finally, we discuss the implications that these data have on the use of C57BL/6 mice and GE mice on this background in studies of cerebellar development or as models of disease.

Abstract TMP104: Upregulation of Tissue-Nonspecific Alkaline Phosphatase in Endothelial Cells Leads to Intracranial Vascular Calcification: A Useful Model of Primary Familial Brain Calcification

Introduction: Vascular calcification is an important pathophysiological factor contributing to neurodegenerative diseases such as primary familial brain calcification (PFBC) and is a potential therapeutic target.

Hypothesis: Given the essential role of tissue-nonspecific alkaline phosphatase (TNAP) in biomineralization, we tested the hypothesis that upregulation of TNAP activity can lead to intracranial calcification.

Methods: We previously reported that overexpression of TNAP in endothelial cells (eTNAP) leads to arterial calcification. Here we analyzed intracranial calcification in eTNAP on the original B6;129 and on the C57BL/6 (B6) genetic backgrounds. Histology was performed on formalin-fixed cryo-preserved tissues. Locomotion testing was performed at 23 weeks and analyzed in Matlab. Gene expression was analyzed by qPCR.

Results: On the B6;129 background, eTNAP mice developed progressive intracranial calcification (0% were affected at 8 weeks, 71% at 13 weeks, and 100% at 23 weeks, n=7 per group). At 23 weeks, calcification was undetectable in the middle cerebral arteries but was associated with microvasculature in the basal ganglia, thalamus, hindbrain, and cerebellum. Calcified lesions were accompanied by astro- and micro-gliosis. Extravasation of IgG into the brain parenchyma was evident in eTNAP; blood-brain barrier was intact in controls (n=3 per group; 23 weeks). There were no significant differences in the locomotion or behavior (open field exploration) between the eTNAP and controls on the B6;129 background (n=6 per group). On B6 background, eTNAP mice displayed significant motor deficits - reduced ambulation (p<0.01), rearing (p< 0.01), speed (p<0.05), and acceleration (p<0.05; n=7-9 per group). There were no changes in osteogenic gene expression or phosphate transporters in eTNAP brains compared with controls. However, we detected significant regional differences between the thalamus and cortex in the levels of RumX2 , Spp1 , SLC17a7 , SLC17a6 of both control and eTNAP mice.

Conclusions: Upregulation of TNAP activity can lead to intracranial vascular calcification. Given the similarities in presentation between eTNAP mice and PFBC patients, this model can advance the understanding of PFBC disease progression.

Abstract TP146: Intracranial Microvascular Calcification: A Cadaveric Study

Introduction: Stroke and brain ischemia are associated with macrovascular calcification. Microvascular calcification may also contribute to cerebrovascular disease, yet its prevalence and pathophysiological significance remain unclear.

Hypothesis: Calcification associated with intracranial microvasculature is prevalent in elderly populations and correlates with calcification of proximal macrovascular supply.

Methods: Tissues were dissected from 20 cadavers (16 female, 4 male; median age = 81 y; range = 56-94 y) unilaterally on the left side. Three vascular territories were examined representing anterior, middle, and posterior brain regions supplied by distal M4 branches of the middle cerebral artery (MCA). Proximally, two putaminal regions supplied by lenticulostriate arteries (from M1 of the MCA) were examined. Extra- and intracranial internal carotid arteries (ICA) and M1 segments of the MCA from the same subjects were previously scored for calcium; those data were used for correlation analysis. A sensitive and specific calcium detection protocol (alizarin red) was used in all studies alongside H&E. Light microscopy was performed to grade small- (< 20 micron) and large-caliber (20-200 micron) vessels for calcification.

Results: Calcification was detected in all subjects, with 95% in small-caliber and 50% in large-caliber microvessels. Non-parametric Spearman correlation analysis revealed significant correlation between calcification of large-caliber microvessels in M4 (but not M1 putaminal vessels) and medial calcification of the MCA (M1 segment; r = 0.6533, p < 0.05). Contrary to our hypothesis, no correlations were found between microvascular calcification and calcification of the ICA. Additionally, no correlations were found between microvascular calcification and atheromatous calcification of either the MCA (M1 segment) or ICA (extra- and intracranial parts).

Conclusions: Our study implies that intracranial microvascular calcification is highly prevalent in elderly populations. Additionally, we discovered significant correlation between microvascular calcification and that of the media in mascrovasculature, suggesting a causal link between medial sclerosis and dysfunction of the neurovascular unit.

Abstract 384: Differential Effects of Niacin and Omega-3 Fatty Acids on HDL-apolipoprotein A-I Exhange and Cholesterol Efflux Capacity in Subjects with Metabolic Syndrome

Objective: Niacin and omega-3 fatty acids are two therapeutic agents that have been extensively studied for their ability to reduce cardiovascular disease risk, but their effectiveness has more recently been called into question. In this study, we investigate whether these agents alone and in combination alter HDL function, in particular, HDL-apolipoprotein A-I exchange (HAE), a measure of HDL dynamics, and serum cholesterol efflux capacity (CEC).

Approach: Fifty-six subjects with metabolic syndrome (MetSyn) were recruited to a double-blind trial and randomized to 16 weeks of treatment with dual placebo, extended release niacin (ERN, 2g/day), prescription omega-3 ethyl esters (P-OM3, 4g/day), or combination. HDL function was assessed at baseline and following 16 weeks of treatment by measuring HAE, macrophage CEC, and ABCA1-specific CEC.

Results: Compared to placebo, ERN and P-OM3 alone significantly increased HAE by 15.1 [8.2, 22.0] (p<0.0001) and 12.4% [5.9, 18.9] ( P <0.0001) respectively while the combination therapy increased HAE by 10.0% [3.2, 16.8] ( P =0.002). When evaluated by HAE:apoA-I ratio (a measure of apoA-I specific activity), ERN increased apoA-I specific activity by 20.1% [4.8, 36.9] ( P =0.008), P-OM3 by 30.1% [14.4, 45.9] ( P< 0.0001), however with combination there was no increase, 9% [-6.6, 26.6] ( P =0.34). Triglyceride-adjusted macrophage CEC showed marginally significant increases with P-OM3 therapy ( P =0.05). No therapy significantly improved ABCA1-specific CEC.

Conclusions: Much of the effect of ERN on HDL function can be attributed to this therapy raising apoA-I levels, but P-OM3 raises HDL function by independent means, increasing apoA-I specific activity. Future investigation is needed to determine whether interaction between ERN and P-OM3 therapies in combination reduces their overall effectiveness.

Overexpression of tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells accelerates coronary artery disease in a mouse model of familial hypercholesterolemia

OBJECTIVE

Overexpression of tissue-nonspecific alkaline phosphatase (TNAP) in endothelium leads to arterial calcification in mice. The purpose of this study was to examine the effect of elevated endothelial TNAP on coronary atherosclerosis. In addition, we aimed to examine endogenous TNAP activity in human myocardium.

APPROACH AND RESULTS

A vascular pattern of TNAP activity was observed in human non-failing, ischemic, and idiopathic dilated hearts (5 per group); no differences were noted between groups in this study. Endothelial overexpression of TNAP was achieved in mice harboring a homozygous recessive mutation in the low density lipoprotein receptor (whc allele) utilizing a Tie2-cre recombinase (WHC-eTNAP mice). WHC-eTNAP developed significant coronary artery calcification at baseline compared WHC controls (4312 vs 0μm2 alizarin red area, p<0.001). Eight weeks after induction of atherosclerosis, lipid deposition in the coronary arteries of WHC-eTNAP was increased compared to WHC controls (121633 vs 9330μm2 oil red O area, p<0.05). Coronary lesions in WHC-eTNAP mice exhibited intimal thickening, calcifications, foam cells, and necrotic cores. This was accompanied by the reduction in body weight and left ventricular ejection fraction (19.5 vs. 23.6g, p<0.01; 35% vs. 47%, p<0.05). In a placebo-controlled experiment under atherogenic conditions, pharmacological inhibition of TNAP in WHC-eTNAP mice by a specific inhibitor SBI-425 (30mg*kg-1*d-1, for 5 weeks) reduced coronary calcium (78838 vs.144622μm2) and lipids (30754 vs. 77317μm2); improved body weight (22.4 vs.18.8g) and ejection fraction (59 vs. 47%). The effects of SBI-425 were significant in the direct comparisons with placebo but disappeared after TNAP-negative placebo-treated group was included in the models as healthy controls.

CONCLUSIONS

Endogenous TNAP activity is present in human cardiac tissues. TNAP overexpression in vascular endothelium in mice leads to an unusual course of coronary atherosclerosis, in which calcification precedes lipid deposition. The prevalence and significance of this mechanism in human atherosclerosis requires further investigations.

Apolipoprotein A-I exchange is impaired in metabolic syndrome patients asymptomatic for diabetes and cardiovascular disease

OBJECTIVE

We tested the hypothesis that HDL-apolipoprotein A-I exchange (HAE), a measure of high-density lipoprotein (HDL) function and a key step in reverse cholesterol transport (RCT), is impaired in metabolic syndrome (MetSyn) patients who are asymptomatic for diabetes and cardiovascular disease. We also compared HAE with cell-based cholesterol efflux capacity (CEC) to address previous reports that CEC is enhanced in MetSyn populations.

METHODS

HAE and ABCA1-specific CEC were measured as tests of HDL function in 60 MetSyn patients and 14 normolipidemic control subjects. Predictors of HAE and CEC were evaluated with multiple linear regression modeling using clinical markers of MetSyn and CVD risk.

RESULTS

HAE was significantly reduced in MetSyn patients (49.0 ± 10.9% vs. 61.2 ± 6.1%, P < 0.0001), as was ABCA1-specific CEC (10.1 ± 1.6% vs. 12.3 ± 2.0%, P < 0.002). Multiple linear regression analysis identified apoA-I concentration as a significant positive predictor of HAE, and MetSyn patients had significantly lower HAE per mg/dL of apoA-I (P = 0.004). MetSyn status was a negative predictor of CEC, but triglyceride (TG) was a positive predictor of CEC, with MetSyn patients having higher CEC per mg/dL of TG, but lower overall CEC compared to controls.

CONCLUSIONS

MetSyn patients have impaired HAE that contributes to reduced capacity for ABCA1-mediated CEC. MetSyn status is inversely correlated with CEC but positively correlated with TG, which explains the contradictory results from earlier MetSyn studies focused on CEC. HAE and CEC are inhibited in MetSyn patients over a broad range of absolute apoA-I and HDL particle levels, supporting the observation that this patient population bears significant residual cardiovascular disease risk.

Abstract 495: Mouse Model of Mesenteric Ischemia Secondary to Vascular Calcification and Atherosclerosis

Objective: Atherosclerosis is a leading cause of chronic mesenteric ischemia (CMI), defined as intestinal hypoperfusion resulting from stenosis of mesenteric arteries. Symptoms of CMI range from non-specific abdominal pain and weight loss to aversion of food resulting in cachexia. In this study we aim to define intestinal ischemia and its effects on gastrointestinal structure and function in an in vivo model of atherosclerosis.

Hypothesis: Overexpression of tissue-nonspecific alkaline phosphatase (TNAP) under conditions of hypercholesterolemia in a mouse model will lead to atherosclerosis causing intestinal ischemia.

Methods and Results: We have previously established that endothelial TNAP overexpression (eTNAP) results in calcification of medium-sized arteries including mesenteric. In this study eTNAP was combined with a point mutation in the low-density lipoprotein receptor ( ldlr ^WHC). When fed an atherogenic diet (Paigen’s diet, starting at 8 weeks of age), WHC-eTNAP mice developed acute body weight loss (>15% from baseline), whereas WHC mice continued to gain weight. Examination of the mesenteries of WHC-eTNAP demonstrated eccentric vascular remodeling and stiffening, as well as calcification of atherosclerotic plaques (n=4). Mesenteric arteries of WHC were not affected (n=3). WHC-eTNAP (n=2) mice developed extensive atherosclerosis of submucosal arterioles in the colon where most vessels were narrowed or occluded. Examination of the small intestine in WHC-eTNAP mice showed structurally distressed villi accompanied with an increase in goblet cells and fragmentation of the epithelial layer possibly reflecting cell death. The colon demonstrated loss of goblet cells and signs of denuding of the epithelium.

Conclusion: Atherosclerosis induced by overexpression of TNAP causes occlusion of mesenteric arteries as well as structural pathology in the small and large intestine

Abstract 426: Overexpression of Tissue-nonspecific Alkaline Phosphatase (TNAP) Accelerates Coronary Artery Disease in the Setting of Hypercholesterolemia in Mice

Objective: Vascular calcification in asymptomatic individuals is an independent predictor of coronary heart disease (CHD). It is therefore plausible that vascular calcification plays a direct pathophysiological role in atherosclerosis, an underlying cause of CHD. The purpose of this study was to examine the contribution that vascular calcification has on the development of coronary atherosclerosis in a mouse model of familial hypercholesterolemia.

Approach and Results: Calcification was induced by overexpression of tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells of mice harboring a point mutation in the low density lipoprotein receptor ( ldlr, wicked high cholesterol, WHC). Mice were fed an atherogenic diet; echocardiographic and biochemical data were collected longitudinally. Atherosclerosis and vascular calcification were analyzed histologically in the aorta, aortic sinus and coronary arteries. TNAP mice were also treated with a combination of an atherogenic diet and a specific inhibitor of TNAP (SBI-425). Combined with the ldlr mutation and an atherogenic diet, TNAP-driven arterial calcification led to severe atherosclerosis with 100% morbidity characterized by occlusive coronary artery disease, pathological cardiac hypertrophy with dilated LV and reduced ejection fraction (EF). We detected an interaction between vascular calcification and atherosclerosis in mice with endothelial TNAP overexpression. This interaction was particularly prominent in coronary circulation. Targeting TNAP activity therapeutically helped improve survival and heart function of endothelial TNAP overexpressor mice, however the incomplete inhibition of TNAP by SBI-425 was a limitation of this study.

Conclusions: Vascular calcification via TNAP overexpression in endothelial cells promotes coronary atherosclerosis and is pathogenic under conditions of hypercholesterolemia.

Abstract 572: The Effect of Inflammation and Soluble Epoxide Hydrolase Inhibition on Fatty Acid Epoxide Incorporation Into VLDL

Objective: We have previously observed fatty acid epoxides, a class of potent anti-inflammatory oxylipins, in circulating VLDL. The source of these epoxides is unknown. Cytochrome P450 (CYP450) produces them via oxygenation of polyunsaturated fatty acids (PUFAs), and soluble epoxide hydrolase (sEH) converts them to diols. Our objectives were 1) to investigate if incorporation of epoxides into VLDL occurs via hepatic VLDL synthesis and 2) to determine if incorporation is modulated by inflammation or by inhibition of hepatic sEH.

Approach and Results: A 2х2 factorial design was used for treatment assignment. Livers were isolated from rats treated with pro-inflammatory lipopolysaccharide (LPS, 10 mg/kg ip) or saline. AUDA, an inhibitor of sEH (10 μM), was included or excluded in the perfusate (Control, N=3; LPS, N=4; AUDA, N=4; LPS+AUDA, N=4). Livers were perfused for 180 minutes. VLDL was isolated by ultra-centrifugation, then analyzed by LC-MS/MS for oxylipin content. Analyzed epoxides and diols were derived from alpha-linolenic acid (ALA), linoleic acid (LA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Two-way ANOVA’s were used with triglyceride concentration as a covariate. Concentrations (nM) are reported as mean [95% CI]. DHA-derived epoxides increased with AUDA treatment (3.91 [3.01, 5.07]) compared to livers without AUDA (2.06 [1.58, 2.67]) (p=0.004), but other epoxides were unchanged by AUDA. EPA and ALA-derived epoxides decreased with LPS treatment (0.32 [0.22, 0.47]; 2.44 [2.07, 2.87]) compared to animals without LPS (0.73 [0.46, 1.16]; 3.28 [2.71, 3.96]) (p=0.01; 0.02). AA and DHA-derived diols decreased with LPS treatment (1.01 [0.82, 1.25]; 0.21 [0.17, 0.26]) compared to animals without LPS (1.46 [1.15, 1.86]; 0.31 [0.24, 0.39]) (p=0.03; 0.03).

Conclusions: Treatment with LPS and AUDA have significant effects on incorporation of epoxides and diols into VLDL, supporting hepatic incorporation controlled by inflammation. Inflammation decreased select EPA- and ALA-derived epoxides. In contrast, sEH inhibition increased only DHA-derived epoxides. Surprisingly, in VLDL only epoxides derived from omega-3 fatty acids were affected by either inflammation or inhibition of sEH.

Modified Low-Dose Triiodo-L-thyronine Therapy Safely Improves Function Following Myocardial Ischemia-Reperfusion Injury

Background: We have shown that thyroid hormones (THs) are cardioprotective and can be potentially used as safe therapeutic agents for diabetic cardiomyopathy and permanent infarction. However, no reliable, clinically translatable protocol exists for TH treatment of myocardial ischemia-reperfusion (IR) injury. We hypothesized that modified low-dose triiodo-L-thyronine (T3) therapy would confer safe therapeutic benefits against IR injury.

Methods: Adult female rats underwent left coronary artery ligation for 60 min or sham surgeries. At 2 months following surgery and T3 treatment (described below), the rats were subjected to functional, morphological, and molecular examination.

Results: Following surgery, the rats were treated with T3 (8 μg/kg/day) or vehicle in drinking water ad libitum following IR for 2 months. Oral T3 significantly improved left ventricular (LV) contractility, relaxation, and relaxation time constant, and decreased beta-myosin heavy chain gene expression. As it takes rats ~6 h post-surgery to begin drinking water, we then investigated whether modified T3 dosing initiated immediately upon reperfusion confers additional improvement. We injected an intraperitoneal bolus of T3 (12 μg/kg) upon reperfusion, along with low-dose oral T3 (4.5 μg/kg/day) in drinking water for 2 months. Continuous T3 therapy (bolus + low-dose oral) enhanced LV contractility compared with oral T3 alone. Relaxation parameters were also improved compared to vehicle. Importantly, these were accomplished without significant increases in hypertrophy, serum free T3 levels, or blood pressure.

Conclusions: This is the first study to provide a safe cardiac therapeutic window and optimized, clinically translatable treatment-monitoring protocol for myocardial IR using commercially available and inexpensive T3. Low-dose oral T3 therapy supplemented with bolus treatment initiated upon reperfusion is safer and more efficacious.

Abstract 462: Transgenic Overexpression of Tissue-nonspecific Alkaline Phosphatase in Monocytes/Macrophages Induces Calcification of Atherosclerotic Plaques

Introduction: Calcification of atherosclerotic plaques is associated with different histopathological and clinical manifestations. Microcalcification promotes inflammation and increases plaque instability, whereas macrocalcification is associated with stable fibroatheroma. The mechanisms of initiation and progression of calcification in atherosclerosis are not completely understood.

Hypothesis: Upregulation of tissue-nonspecific alkaline phosphatase (TNAP) in monocytes/macrophages can lead to calcification of atherosclerotic plaques in a mouse model.

Methods: TNAP overexpression was induced from a targeted transgene in Hprt locus utilizing Cre recombinase driven by monocyte-specific LyzM gene promoter. Resultant mice overexpressing TNAP in cells of monocyte/macrophage lineage (TNAP-Tg) were bred with animals bearing low density lipoprotein receptor mutation. Hypercholesterolemia was induced by feeding Paigen diet for ten weeks. Average plaque area and calcification (area %) were determined from histological sections of the aortic root (5-10 sections/sample). Blood flow velocity in the ascending aorta and left ventricular function were assessed by echocardiography.

Results: In the absence of atherosclerosis, no appreciable soft tissue calcification was observed in TNAP-Tg animals (n=2). During progression of atherosclerosis, calcification was detected in the aortic root lesions of TNAP-Tg mice (4.85% of total plaque area) in significant excess compared to controls (0.02%, p<0.001, n=8 per group). Total plaque area in the aortic root was not affected by TNAP overexpression (0.40 mm^2 in TNAP-Tg; 0.38 in controls; p=0.75). Blood flow velocity in the ascending aorta and heart function were not significantly different between groups.

Conclusions: We developed an animal model in which the interaction between early calcium deposition inside atherosclerotic lesions and the stability of such lesions can be studied experimentally.

Transgenic Overexpression of Tissue-Nonspecific Alkaline Phosphatase (TNAP) in Vascular Endothelium Results in Generalized Arterial Calcification

BACKGROUND

Ectopic vascular calcification is a common condition associated with aging, atherosclerosis, diabetes, and/or chronic kidney disease. Smooth muscle cells are the best characterized source of osteogenic progenitors in the vasculature; however, recent studies suggest that cells of endothelial origin can also promote calcification. To test this, we sought to increase the osteogenic potential of endothelial cells by overexpressing tissue-nonspecific alkaline phosphatase (TNAP), a key enzyme that regulates biomineralization, and to determine the pathophysiological effect of endothelial TNAP on vascular calcification and cardiovascular function.

METHODS AND RESULTS

We demonstrated previously that mice transgenic for ALPL (gene encoding human TNAP) develop severe arterial medial calcification and reduced viability when TNAP is overexpressed in smooth muscle cells. In this study, we expressed the ALPL transgene in endothelial cells following endothelial-specific Tie2-Cre recombination. Mice with endothelial TNAP overexpression survived well into adulthood and displayed generalized arterial calcification. Genes associated with osteochondrogenesis (Runx2, Bglap, Spp1, Opg, and Col2a1) were upregulated in the aortas of endothelial TNAP animals compared with controls. Lesions in coronary arteries of endothelial TNAP mice showed immunoreactivity to Runx2, osteocalcin, osteopontin, and collagen II as well as increased deposition of sialoproteins revealed by lectin staining. By 23 weeks of age, endothelial TNAP mice developed elevated blood pressure and compensatory left ventricular hypertrophy with preserved ejection fraction.

CONCLUSIONS

This study presented a novel genetic model demonstrating the osteogenic potential of TNAP-positive endothelial cells in promoting pathophysiological vascular calcification.

Abstract 375: Alkaline Phosphatase-driven Vascular Calcification Interacts with Hypercholesterolemia and Leads to Severe Coronary Atherosclerosis and Heart Failure in Mice

Objective: Asymptomatic calcification of coronary arteries can independently predict future coronary heart disease. It is not yet clear, however, whether the temporal presence of calcification in coronary arteries is pathogenic. We have recently demonstrated that upregulation of tissue-nonspecific alkaline phosphatase (TNAP) in vascular smooth muscle cells in vivo is sufficient to induce medial calcification. The purpose of this study was to test the hypothesis that TNAP-driven intimal calcification can promote coronary atherosclerosis in a mouse model.

Methods: TNAP was overexpressed in endothelial cells in wild type mice and in mice harboring “wicked high cholesterol” (WHC) mutation in the low density lipoprotein receptor. Hypercholesterolemia was induced in WHC mice by feeding an atherogenic diet. Physiological, histological, and biochemical data were collected longitudinally.

Results: In the absence of hypercholesterolemia, pan-endothelial overexpression of TNAP induced systemic generalized arterial calcification with normal calcium and phosphate metabolism, but with elevated blood pressure and physiological left ventricular (LV) hypertrophy. Calcific nodules first appear in the arterial intima and expand into the arterial media. Combined with the WHC mutation and 6-8 weeks on atherogenic diet, TNAP-driven arterial calcification led to severe atherosclerosis with 100% morbidity characterized by occlusive coronary artery disease (histologically), pathological cardiac hypertrophy with LV dilation, and reduced cardiac ejection fraction (EF).

Conclusions: Arterial calcification promotes lipid deposition and is pathogenic when cholesterol is elevated due to genetic and dietary causes.

Abstract 111: HDL-apolipoprotein A-I Exchange Is Impaired in the Metabolic Syndrome

Objective: Metabolic syndrome (MetSyn) is associated with a host of cardiovascular risk factors including increased waist circumference, triglycerides, blood pressure, fasting glucose, and reduced high density lipoprotein cholesterol (HDL-C). Changes in HDL function, especially the ability to participate in reverse cholesterol transport, are more indicative of the atheroprotective properties of HDL compared to HDL-C levels alone. In this study, we determine the association of HDL-apolipoproteinA-I (apoA-I) exchange, a measure of HDL remodeling/apoA-I exchange, with MetSyn and its individual components.

Methods and Results: We analyzed HDL-apoA-I exchange (HAE) in the plasma of 60 well-characterized subjects with MetSyn and 14 healthy control subjects. HAE measurements were obtained using electron paramagnetic resonance (EPR) following incubation of plasma with lipid-freeapoA-I containing a methanethiosulfonate spin label. HAE positively correlated with plasma HDL-C and apoA-I levels, and inversely correlated with fasting blood glucose levels, blood pressure, BMI, and triglycerides. Multiple linear regression showed that HAE is significantly correlated with MetSyn (HAE: r2 = 0.57, P<0.0001), though MetSyn subjects on statins exhibited significantly higher HAE compared to subjects not on statins.

Conclusions: MetSyn has a significant negative impact on HDL remodelin/apoA-I exchange, as measured by HAE. HAE is a strong identifier of MetSyn status even after adjusting for individual components of MetSyn.

Reduced apolipoprotein glycosylation in patients with the metabolic syndrome

Objective

The purpose of this study was to compare the apolipoprotein composition of the three major lipoprotein classes in patients with metabolic syndrome to healthy controls.

Methods

Very low density (VLDL), intermediate/low density (IDL/LDL, hereafter LDL), and high density lipoproteins (HDL) fractions were isolated from plasma of 56 metabolic syndrome subjects and from 14 age-sex matched healthy volunteers. The apolipoprotein content of fractions was analyzed by one-dimensional (1D) gel electrophoresis with confirmation by a combination of mass spectrometry and biochemical assays.

Results

Metabolic syndrome patients differed from healthy controls in the following ways: (1) total plasma - apoA1 was lower, whereas apoB, apoC2, apoC3, and apoE were higher; (2) VLDL - apoB, apoC3, and apoE were increased; (3) LDL - apoC3 was increased, (4) HDL -associated constitutive serum amyloid A protein (SAA4) was reduced (p<0.05 vs. controls for all). In patients with metabolic syndrome, the most extensively glycosylated (di-sialylated) isoform of apoC3 was reduced in VLDL, LDL, and HDL fractions by 17%, 30%, and 25%, respectively (p<0.01 vs. controls for all). Similarly, the glycosylated isoform of apoE was reduced in VLDL, LDL, and HDL fractions by 15%, 26%, and 37% (p<0.01 vs. controls for all). Finally, glycosylated isoform of SAA4 in HDL fraction was 42% lower in patients with metabolic syndrome compared with controls (p<0.001).

Conclusions

Patients with metabolic syndrome displayed several changes in plasma apolipoprotein composition consistent with hypertriglyceridemia and low HDL cholesterol levels. Reduced glycosylation of apoC3, apoE and SAA4 are novel findings, the pathophysiological consequences of which remain to be determined.

Thyroid hormone induces sprouting angiogenesis in adult heart of hypothyroid mice through the PDGF-Akt pathway

Study of physiological angiogenesis and associated signalling mechanisms in adult heart has been limited by the lack of a robust animal model. We investigated thyroid hormone-induced sprouting angiogenesis and the underlying mechanism. Hypothyroidism was induced in C57BL/6J mice by feeding with propylthiouracil (PTU). One year of PTU treatment induced heart failure. Both 12 weeks- (young) and 1 year-PTU (middle age) treatment caused a remarkable capillary rarefaction observed in capillary density. Three-day Triiodothyronine (T3) treatment significantly induced cardiac capillary growth in hypothyroid mice. In cultured left ventricle (LV) tissues from PTU-treated mice, T3 also induced robust sprouting angiogenesis where pericyte-wrapped endothelial cells formed tubes. The in vitro T3 angiogenic response was similar in mice pre-treated with PTU for periods ranging from 1.5 to 12 months. Besides bFGF and VEGF₁₆₄, PDGF-BB was the most robust angiogenic growth factor, which stimulated notable sprouting angiogenesis in cultured hypothyroid LV tissues with increasing potency, but had little effect on tissues from euthyroid mice. T3 treatment significantly increased PDGF receptor beta (PDGFR-β) protein levels in hypothyroid heart. PDGFR inhibitors blocked the action of T3 both on sprouting angiogenesis in cultured LV tissue and on capillary growth in vivo. In addition, activation of Akt signalling mediated in T3-induced angiogenesis was blocked by PDGFR inhibitor and neutralizing antibody. Our results suggest that hypothyroidism leads to cardiac microvascular impairment and rarefaction with increased sensitivity to angiogenic growth factors. T3-induced cardiac sprouting angiogenesis in adult hypothyroid mice was associated with PDGF-BB, PDGFR-β and downstream activation of Akt.

[Synthesis and biological activity of 2,3-secotriterpene acid mono- and diamides]

Four types of amide (C3; C28; C3-C28) conjugates based on 2,3-seco-18alphaH-oleanane and 2,3-secolupane mono- and dicarboxylic acids were synthesized. The range of diamide derivatives was supplemented with C3-C3' and C28-C28' dicondensed amides with two A-secotriterpene backbones educed by reacting monocarboxylic A-secoacids with biogenic amino acid lysine. Compounds with inhibitory action against herpes virus reproduction (EC50 8.7 and 4.1 McM) were found among the synthesized mono- and diamide derivatives containing an ethyl-beta-alaninate fragment. It has been ascertained that diamide with ethyl-beta-alaninate fragment combines anti-herpes virus properties and anti-HIV activity (EC50 5.1 McM). For active compounds, the maximum non-toxic concentration (MNTC)/EC50 ratios ranges from 9.7 to 40.8. The synthesized amide conjugates do not exhibit any marked cytotoxic effects against human tumor cell lines rabdomiosarcoma RD TE32, A549 lung carcinoma and melanoma MS.

Restoration of cardiac tissue thyroid hormone status in experimental hypothyroidism: a dose-response study in female rats

Thyroid hormones (THs) play a pivotal role in regulating cardiovascular homeostasis. To provide a better understanding of the coordinated processes that govern cardiac TH bioavailability, this study investigated the influence of serum and cardiac TH status on the expression of TH transporters and cytosolic binding proteins in the myocardium. In addition, we sought to determine whether the administration of T(3) (instead of T(4)) improves the relationship between THs in serum and cardiac tissue and cardiac function over a short-term treatment period. Adult female Sprague Dawley rats were made hypothyroid by 7 weeks treatment with the antithyroid drug 6-n-propyl-2-thiouracil (PTU). After establishing hypothyroidism, rats were assigned to 1 of 5 graded T(3) dosages plus PTU for a 2-week dose-response experiment. Untreated, age-matched rats served as euthyroid controls. PTU was associated with depressed serum and cardiac tissue T(3) and T(4) levels, arteriolar atrophy, altered TH transporter and cytosolic TH binding protein expression, fetal gene reexpression, and cardiac dysfunction. Short-term administration of T(3) led to a mismatch between serum and cardiac tissue TH levels. Normalization of serum T(3) levels was not associated with restoration of cardiac tissue T(3) levels or cardiac function. In fact, a 3-fold higher T(3) dosage was necessary to normalize cardiac tissue T(3) levels and cardiac function. Importantly, this study provides the first comprehensive data on the relationship between altered TH status (serum and cardiac tissue), cardiac function, and the coordinated in vivo changes in cardiac TH membrane transporters and cytosolic TH binding proteins in altered TH states.

Regulation of gene expression with thyroid hormone in rats with myocardial infarction

Introduction

The expression of hundreds of genes is altered in response to left ventricular (LV) remodeling following large transmural myocardial infarction (MI). Thyroid hormone (TH) improves LV remodeling and cardiac performance after MI. However, the molecular basis is unknown.

Methods

MI was produced by ligation of the left anterior descending coronary artery in female SD rats. Rats were divided into the following groups: (1) Sham MI, (2) MI, and (3) MI+T4 treatment (T4 pellet 3.3 mg, 60 days release, implanted subcutaneously immediately following MI). Four weeks after surgery, total RNA was isolated from LV non-infarcted areas for microarray analysis using the Illumina RatRef-12 Expression BeadChip Platform.

Results

Signals were detected in 13,188 genes (out of 22,523), of which the expression of 154 genes were decreased and the expression of 200 genes were increased in MI rats compared with Sham MI rats (false discovery rate (FDR) <0.05). Compared to MI rats, T4 treatment decreased expression of 27 genes and increased expression of 28 genes. In particular, 6 genes down-regulated by MI and 12 genes up-regulated by MI were reversed by T4. Most of the 55 genes altered by T4 treatment are in the category of molecular function under binding (24) and biological processes which includes immune system process (9), multi-organism process (5) and biological regulation (19) nonexclusively.

Conclusions

These results suggest that altered expression of genes for molecular function and biological process may be involved in the beneficial effects of thyroid hormone treatment following MI in rats.

Radical-regulating and antiviral properties of ascorbic acid and its derivatives

The ability of ascorbic acid and a number of its derivatives to suppress replication of Herpes simplex virus type I was investigated in human rhabdomyosarcoma cell line. In parallel, interaction of the test compounds with carbon- and oxygen-centered radicals formed on radiolysis of hydroxyl-containing organic compounds was studied using the steady state radiolysis method. It has been shown that 2-O-glycoside of ascorbic acid, displaying marked antiviral properties against Herpes simplex virus type I, is also capable of inhibiting fragmentation and recombination reactions of α-hydroxyl-containing carbon-centered radicals while not affecting processes involving oxygen-centered radicals.

Fish oil -- how does it reduce plasma triglycerides?

Long chain omega-3 fatty acids (FAs) are effective for reducing plasma triglyceride (TG) levels. At the pharmaceutical dose, 3.4g/day, they reduce plasma TG by about 25-50% after one month of treatment, resulting primarily from the decline in hepatic very low density lipoprotein (VLDL-TG) production, and secondarily from the increase in VLDL clearance. Numerous mechanisms have been shown to contribute to the TG overproduction, but a key component is an increase in the availability of FAs in the liver. The liver derives FAs from three sources: diet (delivered via chylomicron remnants), de novo lipogenesis, and circulating non-esterified FAs (NEFAs). Of these, NEFAs contribute the largest fraction to VLDL-TG production in both normotriglyceridemic subjects and hypertriglyceridemic, insulin resistant patients. Thus reducing NEFA delivery to the liver would be a likely locus of action for fish oils (FO). The key regulator of plasma NEFA is intracellular adipocyte lipolysis via hormone sensitive lipase (HSL), which increases as insulin sensitivity worsens. FO counteracts intracellular lipolysis in adipocytes by suppressing adipose tissue inflammation. In addition, FO increases extracellular lipolysis by lipoprotein lipase (LpL) in adipose, heart and skeletal muscle and enhances hepatic and skeletal muscle β-oxidation which contributes to reduced FA delivery to the liver. FO could activate transcription factors which control metabolic pathways in a tissue specific manner regulating nutrient traffic and reducing plasma TG. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.

Thyroid hormone promotes remodeling of coronary resistance vessels

Low thyroid hormone (TH) function has been linked to impaired coronary blood flow, reduced density of small arterioles, and heart failure. Nonetheless, little is known about the mechanisms by which THs regulate coronary microvascular remodeling. The current study examined the initial cellular events associated with coronary remodeling induced by triiodothyronine (T3) in hypothyroid rats. Rats with established hypothyroidism, eight weeks after surgical thyroidectomy (TX), were treated with T3 for 36 or 72 hours. The early effects of T3 treatment on coronary microvasculature were examined morphometrically. Gene expression changes in the heart were assessed by quantitative PCR Array. Hypothyroidism resulted in arteriolar atrophy in the left ventricle. T3 treatment rapidly induced small arteriolar muscularization and, within 72 hours, restored arteriolar density to control levels. Total length of the capillary network was not affected by TX or T3 treatment. T3 treatment resulted in the coordinate regulation of Angiopoietin 1 and 2 expression. The response of Angiopoietins was consistent with vessel enlargement. In addition to the well known effects of THs on vasoreactivity, these results suggest that THs may affect function of small resistance arteries by phenotypic remodeling of vascular smooth muscle cells (VSMC).

[Synthesis of dihydroquinopymaric acid conjugates with amino acids]

Synthesis of dihydroquinopymaric acid amides and their 2beta-succinyl and 2beta-phthalyl derivatives containing residues of amino acids was carried out for the first time. Antiviral properties of the compounds synthesized were investigated.

The Nfkb1 and Nfkb2 proteins p105 and p100 function as the core of high-molecular-weight heterogeneous complexes

Nfkb1 and Nfkb2 proteins p105 and p100 serve both as NF-kappaB precursors and inhibitors of NF-kappaB dimers. In a biochemical characterization of endogenous cytoplasmic and purified recombinant proteins, we found that p105 and p100 assemble into high-molecular-weight complexes that contribute to the regulation of all NF-kappaB isoforms. Unlike the classical inhibitors IkappaBalpha, -beta, and -epsilon, high-molecular-weight complexes of p105 and p100 proteins bind NF-kappaB subunits in two modes: through direct dimerization of Rel homology domain-containing NF-kappaB polypeptides and through interactions of the p105 and p100 ankyrin repeats with preformed NF-kappaB dimers, thereby mediating the bona fide IkappaB activities, IkappaBgamma and IkappaBdelta. Our biochemical evidence suggests an assembly pathway in which kinetic mechanisms control NF-kappaB dimer formation via processing and assembly of large complexes that contain IkappaB activities.

[New betulin derivatives in combination with rimantadine for inhibition of influenza virus reproduction]

The preliminary studies mainly revealed comparable inhibition activities of 3-oxime of betulonic acid, 3beta-O-acetyl-28-O-hemiphthalate of betulin and 3,28-dioxime of betulin against reproduction of influenza viruses A (H1N1), A (H7N1), A (H3N2) and B, as well as against the strains of influenza virus A (H1N1) with intrinsic resistance to rimantadine and A (H7N1) with acquired resistance to the drug. The level of the activity depended on the system used for the virus reproduction. The highest level was observed under conditions providing higher permissibivity, i.e. in the chick embryo fibroblast cell culture for A (H7N1) and in fragments of chick embryo chorioallantoic membranes (for all the viruses). In the experiments with virus A/FPV/Rostock/34 (H7N1) in the chick embryo fibroblast cell culture the average effective concentrations (EC50) of the triterpene compounds were 10.4-17.5 mcM in comparison to EC50 of rimantadine (0.014 mcM). The use of every of the compounds in combination with rimantadine resulted in a 2-16 times decrease of their EC50 and correction of the concentration-effect relation of rimantadine. However, when rimantadine was used alone within the higher range of the nontoxic concentrations (11.6-57.6 mcM). its antiviral properties were significantly less pronounced. As a result the virus titer difference in comparison to the control within the above range of the rimantadine concentrations increased from < 1 to > 2.35 Ig PPU/ml and the relations of the maximal tolerance concentrations of the compounds to their EC50 increased 1.7-15.9 times.

Stabilization of RelB requires multidomain interactions with p100/p52

The NF-kappaB family member RelB has many properties not shared by other family members such as restricted subunit association and lack of regulation by the classical IkappaB proteins. We show that the protein level of RelB is significantly reduced in the absence of p100 and reduced even more when both p100 and p105 are absent. RelB stabilizes itself by directly interacting with p100, p105, and their processed products. However, RelB forms complexes with its partners using different interaction modes. Although the C-terminal ankyrin repeat domain of p105 is not involved in the RelB-p105 complex formation, all domains and flexible regions of each protein are engaged in the RelB-p100 complex. In several respects the RelB-p52 and RelB-p100 complexes are unique in the NF-kappaB family. The N-terminal domain of p100/p52 interacts with RelB but not RelA. The transcriptional activation domain of RelB, but not RelA, directly interacts with the processing region of p100. These unique protein-protein contacts explain why RelB prefers p52 as its dimeric partner for transcriptional activity and is retained in the cytoplasm as an inhibited complex by p100. This association-mediated stabilization of RelB implies a possible role for RelB in the processing of p100 into p52.

Inducible nitric oxide synthase, Nos2, does not mediate optic neuropathy and retinopathy in the DBA/2J glaucoma model

Background

Nitric oxide synthase 2 (NOS2) contributes to neural death in some settings, but its role in glaucoma remains controversial. NOS2 is implicated in retinal ganglion cell degeneration in a rat glaucoma model in which intraocular pressure (IOP) is experimentally elevated by blood vessel cauterization, but not in a rat glaucoma model where IOP was elevated by injection of hypertonic saline. To test the importance of NOS2 for an inherited glaucoma, in this study we both genetically and pharmacologically decreased NOS2 activity in the DBA/2J mouse glaucoma model.

Methods

The expression of Nos2 in the optic nerve head was analyzed at both the RNA and protein levels at different stages of disease pathogenesis. To test the involvement of Nos2 in glaucomatous neurodegeneration, a null allele of Nos2 was backcrossed into DBA/2J mice and the incidence and severity of glaucoma was assessed in mice of each Nos2 genotype. Additionally, DBA/2J mice were treated with the NOS2 inhibitor aminoguanidine and the disease compared to untreated mice.

Results

Optic nerve head Nos2 RNA levels varied and increased during moderate but decreased at early and severe stages of disease. Despite the presence of a few NOS2 positive cells in the optic nerve head, NOS2 protein was not substantially increased during the glaucoma. Genetic deficiency of Nos2 or aminoguanidine treatment did not alter the IOP profile of DBA/2J mice. Additionally, neither Nos2 deficiency nor aminoguanidine had any detectable affect on the glaucomatous optic nerve damage.

Conclusion

Glaucomatous neurodegeneration in DBA/2J mice does not require NOS2 activity. Further experiments involving various models are needed to assess the general importance of Nos2 in glaucoma.

[Synthesis and antiviral activity of lupane triterpenoids with modified cycle E]

A reductive transformation of the peroxide products of ozonolysis of derivatives of 3beta-O-acetyl-22(17-->28)-abeo-lupa-17(28),20(29)-diene and the subsequent intramolecular ketalization led to a compound with a trioxane fragment. This is a new approach to a skeletal modification of triterpenoid cycle E. An activity of the synthesized compounds was found toward the viruses of type A influenza and herpes simplex.

Col4a1 mutation causes endoplasmic reticulum stress and genetically modifiable ocular dysgenesis

Ocular anterior segment dysgenesis (ASD) is a complex and poorly understood group of conditions. A large proportion of individuals with ASD develop glaucoma, a leading cause of blindness resulting from retinal ganglion cell death. Optic nerve hypoplasia is thought to have distinct causes and is a leading cause of blindness in children. Here, we show that a mutation in the type IV collagen alpha 1 (Col4a1) gene can cause both ASD and optic nerve hypoplasia. COL4A1 is a major component of almost all basement membranes. The mutation results in non-secretion of the mutant COL4A1 proteins, which instead accumulate within cells. Basement membrane abnormalities may, therefore, contribute to the phenotype. The mutation also induces endoplasmic reticulum stress and so intracellular stress may contribute to pathogenesis. The overall consequence of the Col4a1 mutation depends on genetic context. In one genetic context, the mutation causes severe ASD with intraocular pressure abnormalities and optic nerve hypoplasia. In a different genetic context, both the ASD and optic nerve hypoplasia are rescued, and we have identified a single dominant locus that confers the phenotypic modification.