ABCA1 mRNA Expression Research Articles

Deficiency of Calpain-1 attenuates atherosclerotic plaque and calcification and improves vasomotor dysfunction in Apolipoprotein E knockout mice through inhibiting inflammation.

Atherosclerosis (AS) and atherosclerotic calcification (AC) are closely related to the cardiovascular diseases, largely due to its induction of vasomotor dysfunction. We previously reported that Calpain-1 inhibitor attenuated AS and AC. The present study was designed to investigate the effects and potential mechanisms of Calpain-1 knockout (Calpain-1 KO) in Apolipoprotein E KO (ApoE KO) mice on AS, AC, aortic vasomotor function as well as the liver dysfunction. We hybridized ApoE KO mice with Calpain-1 KO mice to obtain ApoE/Calpain-1 double KO (A×C DKO) mice. The formation of AS and AC was evaluated and liver function was determined. Aortic vasomotor function was assessed. Contents of TNF-α, IL-6, IL-18, IL-1β and NO and the activity of AST, ALT, ALP and eNOS in serum were quantified. The mRNA expression of CD68, SR-A, CD36, PPAR-γ, LXR-α, ABCA1, BMP-2, OPN, ALP and Runx2 in aorta and/or liver were measured. The results showed that in comparison to C57 mice, ApoE KO mice demonstrated the significant increases in the areas of AS and AC, the increases in the mRNA expression of CD68 in the aorta, the increases in the AST, ALT and ALP activity in serum. ApoE KO mice also showed the dysfunction of the aortic contraction induced by phenylephrine and of the relaxation induced by acetylcholine. However, compared with ApoE KO mice, A×C DKO mice exhibited the significant attenuation of AS and AC and the downregulation of mRNA expression of CD68 in aorta. A×C DKO mice revealed the reduction of AST, ALT and ALP activity in serum, the improvements in aortic contraction and relaxation as well as the increases in eNOS activity and NO content in serum. A×C DKO mice also showed the decreases in the contents of TNF-α, IL-6, IL-18 and IL-1β in serum. The mRNA expression of CD68 in aorta, SR-A and CD36 in both aorta and liver of A×C DKO mice was downregulated, while that of PPAR-γ, LXR-α, and ABCA1 was upregulated in comparison of ApoE KO mice. In addition, the mRNA expression of BMP-2, OPN, ALP and Runx2 in aorta of A×C DKO mice was downregulated in comparison of ApoE KO mice. The results suggested that deficiency of Calpain-1 attenuated the formation of AS and AC and improved vasomotor and liver dysfunction in ApoE KO mice through anti-inflammation, and modulation of the mRNA expression of genes related to AS and AC.

Myricitrin Alleviates Hypercholesterolemia and Non-Alcoholic Fatty Liver Disease in High Cholesterol Diet-Fed Mice

Background/Objectives: This research investigated the effects of myricitrin on hypercholesterolemia and non-alcoholic fatty liver disease (NAFLD) in mice given a high-cholesterol diet (HCD). Methods: C57BL/6J mice were maintained for 20 weeks on an HCD with or without myricitrin. Results: Myricitrin had no impact on the food consumption, body weight, or plasma triglyceride concentrations. However, myricitrin-supplemented mice had lower plasma total cholesterol (TC) concentrations and LDL + VLDL-cholesterol/TC proportion, and higher HDL-cholesterol/TC proportion than control mice, which resulted in a markedly decreased atherogenic index. Moreover, the levels of plasma C-reactive protein, oxidized LDL, lipoprotein(a), and plasminogen activator inhibitor-1, which are indicators for cardiovascular disease (CVD), were reduced, while levels of plasma paraoxonase, a cardioprotective enzyme, were greater in myricitrin-supplemented mice than in control mice. Myricitrin also meaningfully reduced liver weight and hepatic cholesterol content, and slightly alleviated fatty liver and fibrosis caused by an HCD. The plasma and hepatic cholesterol-lowering effects of myricitrin were partly associated with decreased activities of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase and acyl-CoA:cholesterol acyltransferase, which are involved in cholesterol synthesis and esterification, respectively, as well as mRNA expression. Myricitrin also altered other hepatic genes implicated in cholesterol homeostasis, including the downregulation of SREBP2 and ABCA1 mRNA expression and the upregulation of LDLR mRNA expression. Moreover, myricitrin decreased TBARS levels in the liver and erythrocytes by activating antioxidant enzymes (SOD and catalase). Conclusions: These results indicate that dietary myricitrin may offer therapeutic benefits for HCD-caused hypercholesterolemia and NAFLD, and may help reduce CVD risk.

NMDA Suppresses Pancreatic ABCA1 Expression through the MEK/ERK/LXR Pathway in Pancreatic Beta Cells.

Dysfunction or loss of pancreatic β cells can cause insulin deficiency and impaired glucose regulation, resulting in conditions like type 2 diabetes. The ATP-binding cassette transporter A1 (ABCA1) plays a key role in the reverse cholesterol transport system, and its decreased expression is associated with pancreatic β cell lipotoxicity, resulting in abnormal insulin synthesis and secretion. Increased glutamate release can cause glucotoxicity in β cells, though the detailed mechanisms remain unclear. This study investigated the effect of N-methyl-D-aspartic acid (NMDA) on ABCA1 expression in INS-1 cells and primary pancreatic islets to elucidate the signaling mechanisms that suppress insulin secretion. Using Western blotting, microscopy, and biochemical analyses, we found that NMDA activated the mitogen-activated protein kinase (MEK)-dependent pathway, suppressing ABCA1 protein and mRNA expression. The MEK-specific inhibitor PD98059 restored ABCA1 promoter activity, indicating the involvement of the extracellular signal-regulated kinase (MEK/ERK) pathway. Furthermore, we identified the liver X receptor (LXR) as an effector transcription factor in NMDA regulation of ABCA1 transcription. NMDA treatment increased cholesterol and triglyceride levels while decreasing insulin secretion, even under high-glucose conditions. These effects were abrogated by treatment with PD98059. This study reveals that NMDA suppresses ABCA1 expression via the MEK/ERK/LXR pathway, providing new insights into the pathological suppression of insulin secretion in pancreatic β cells and emphasizing the importance of investigating the role of NMDA in β cell dysfunction.

The Lian-Dou-Qing-Mai Formula activates the PPARγ-LXRα-ABCA1/ABCG1 pathway by regulating IL-10, leading to the promotion of cholesterol efflux and a reduction in atherosclerotic plaques.

To observe the effect of the Lian-Dou-Qing-Mai (LDQM) formula on lipid metabolism in mice and explore its mechanism from the perspective of regulating the PPARγ/LXRα/ABCA1 signaling pathway. THP-1 cells were induced to transform into foam cells with ox-LDL. Atherosclerosis (AS) models were constructed using a high-fat diet in ApoE-/- mice. Detection kits were used to evaluate triglyceride (TG) and total cholesterol (TC) content; TNF-α, MCP-1, MMP-9, TMP-1, PPARγ, LXRα, ABCA1, and ABCG1 mRNA and protein expression were identified using real-time PCR and western blot. Interleukin-10 (IL-10) blood levels were measured using an enzyme-linked immunosorbent assay (ELISA), and aortic plaque development and lipid deposition were seen using hematoxylin and eosin (HE) and oil red O staining, respectively. In the cell model, LDQM could inhibit the formation of THP-1 macrophage-derived foam cells and the expression of inflammatory factors, promote macrophage cholesterol efflux, increase the expression of IL-10, and activate the PPARγ-LXRα-ABCA1/ABCG1 pathway. Additional IL-10 treatment further promotes LDQM-induced cholesterol efflux in THP-1 cells; in In vivo models, LDQM inhibited the area of atherosclerotic lesions, aortic lipid deposition, and inflammation levels in ApoE-/- mice through IL-10, and activated the expression level of the PPARγ-LXRα-ABCA1/ABCG1 pathway. LDQM may affect the PPARγ/LXRα/ABCA1 signaling pathway through IL-10, regulate lipid metabolism, reduce serum inflammatory expression and lipid deposition, and improve the formation of atheroplaques.

Decreased mRNA expression of NR1H3 and ABCA1 in pulmonary tuberculosis patients from population of Punjab, India.

Mycobacterium tuberculosis (MTB) is the causative organism of tuberculosis. Cholesterol is a crucial carbon source required for the survival of MTB in host cells. Transcription factor NR1H3 along with its important target genes ABCA1 and ApoE play important role in removal of extra cholesterol from cells. Changes in the gene expression of NR1H3, ABCA1 and ApoE can affect cholesterol homeostasis and thus the survival of MTB in host cells.Therefore, the present study was designed to analyze the mRNA expression of NR1H3, ABCA1 and ApoE in pulmonary TB (PTB) patients from the population of Punjab, India. In this study, mRNA expression of the transcription factor NR1H3 and its target genes ABCA1 and ApoE was analyzed in 89 subjects, including 41 PTB patients and 48 healthy controls (HCs) by real-time quantitative PCR. It was found that the mRNA expression of both NR1H3 and ABCA1 genes was significantly lower in TB patients than in HCs (p < 0.001). Even after sex-wise stratification of the subjects, mRNA expression of NR1H3 and ABCA1 was found to be down-regulated in both male and female TB patients. No significant difference was observed in expression of ApoE (p = 0.98). The present study found that the mRNA expression of NR1H3 and ABCA1 is down-regulated in TB patients from Punjab state of India.

C1q/Tumor Necrosis Factor-Related Protein-9 Enhances Macrophage Cholesterol Efflux and Improves Reverse Cholesterol Transport via AMPK Activation.

Cholesterol efflux from foam cells in atherosclerotic plaques is crucial for reverse cholesterol transport (RCT), an important antiatherogenic event. ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are key receptors in the cholesterol efflux pathway. C1q/tumor necrosis factor-related protein-9 (CTRP9) is a newly discovered adipokine and exhibits an atheroprotective activity. However, the role of CTRP9 in RCT still remains unknown. In this work, we investigated the effect of subcutaneous administration of CTRP9 protein on RCT and atherosclerotic lesion formation in ApoE-/- mice fed with a high-fat diet. CTRP9-dependent regulation of cholesterol efflux and ABC transporters in RAW 264.7 foam cells was determined. Our results showed that CTRP9 protein decreased atherosclerotic lesions, increased cholesterol efflux, and upregulated liver ABCA1 and ABCG1 expression in ApoE-/- mice. CTRP9 treatment dose-dependently increased mRNA and protein expression of ABCA1, ABCG1, and LXR-α in RAW 264.7 foam cells. Moreover, the expression and phosphorylation of AMPK was potentiated upon CTRP9 treatment. Notably, CTRP9-induced cholesterol efflux and upregulation of ABCA, ABCG1, and LXR-α were impaired when AMPK was knocked down. AMPK depletion restored cholesterol accumulation in CTRP9-treated RAW 264.7 cells. Taken together, subcutaneous injection is an effective novel delivery route for CTRP9 protein, and exogenous CTRP9 can facilitate cholesterol efflux and promote RCT in an animal model of atherosclerosis. The atheroprotective activity of CTRP9 is mediated through the activation of AMPK signaling.

Expression of ATP-Binding Cassette Transporter A1 (ABCA1) in Eyelid Tissues and Meibomian Gland Epithelial Cells.

To validate the adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) expression and distribution in human eyelid tissues and meibomian gland epithelial cells. Meibomian gland tissues from human eyelids were isolated by collagenase A digestion and cultured in defined keratinocyte serum-free medium (DKSFM). Infrared imaging was used to analyze the general morphology of meibomian glands. Hematoxylin and eosin (H&E) staining and Oil Red O staining were used to observe the morphological structure and lipid secretion in the human meibomian gland tissues. Quantitative real-time polymerase chain reaction, western blotting, and immunostaining were used to detect the mRNA and protein expression and cytolocalization of ABCA1 in the meibomian gland tissues and cultured cells. The degree of loss of human meibomian gland tissue was related to age. Meibomian gland lipid metabolism was also associated with age. Additionally, human meibomian gland tissues express ABCA1 mRNA and protein; glandular epithelial cells express more ABCA1 mRNA and protein than acinar cells, and their expression in acinar cells decreases with differentiation. Furthermore, the expression of ABCA1 was downregulated in abnormal meibomian gland tissues. ABCA1 was mainly localized on the cell membrane in primary human meibomian gland epithelial cells (pHMGECs), whereas it was localized in the cytoplasm of immortalized human meibomian gland epithelial cells (iHMGECs). The mRNA and protein levels of ABCA1 in pHMGECs were higher than those in iHMGECs. Meibomian gland tissues of the human eyelid degenerate with age. ABCA1 expression in acinar cells decreases after differentiation and plays an important role in meibomian gland metabolism.

Elder (Sambucus nigra), identified by high-content screening, counteracts foam cell formation without promoting hepatic lipogenesis

Cholesterol deposition in intimal macrophages leads to foam cell formation and atherosclerosis. Reverse cholesterol transport (RCT), initiated by efflux of excess cholesterol from foam cells, counteracts atherosclerosis. However, targeting RCT by enhancing cholesterol efflux was so far accompanied by adverse hepatic lipogenesis. Here, we aimed to identify novel natural enhancers of macrophage cholesterol efflux suitable for the prevention of atherosclerosis. Plant extracts of an open-access library were screened for their capacity to increase cholesterol efflux in RAW264.7 macrophages trace-labeled with fluorescent BODIPY-cholesterol. Incremental functional validation of hits yielded two final extracts, elder (Sambucus nigra) and bitter orange (Citrus aurantium L.) that induced ATP binding cassette transporter A1 (ABCA1) expression and reduced cholesteryl ester accumulation in aggregated LDL-induced foam cells. Aqueous elder extracts were subsequently prepared in-house and both, flower and leaf extracts increased ABCA1 mRNA and protein expression in human THP-1 macrophages, while lipogenic gene expression in hepatocyte-derived cells was not induced. Chlorogenic acid isomers and the quercetin glycoside rutin were identified as the main polyphenols in elder extracts with putative biological action. In summary, elder flower and leaf extracts increase macrophage ABCA1 expression and reduce foam cell formation without adversely affecting hepatic lipogenesis.

Maternal high-calorie diet feeding programs hepatic cholesterol metabolism and Abca1 promoter methylation in the early life of offspring

Maternal high-calorie diet feeding can dramatically increase the susceptibility of metabolic diseases in offspring. However, whether maternal high-calorie diet feeding can program hepatic cholesterol metabolism in the early life of offspring is less understood, and the epigenetic mechanisms underlying this intergenerational effect, especially during the early life of offspring, are unknown. Female C57BL/6J mice were randomly assigned to a high-calorie diet or control diet before and during gestation, and lactation. Lipid metabolism was evaluated in male offspring at weaning. Gene expressions and quantitative methylation levels of key genes associated with hepatic cholesterol metabolism were further evaluated in offspring at weaning age. We found that maternal high-calorie diet feeding resulted in higher body weight, hypercholesterolemia, elevated total cholesterol in liver homogenates, and fat deposits in the liver in offspring at weaning. For key genes that regulate cholesterol metabolism in liver, we showed lower Hmgcr and Ldlr, and higher Abca1 mRNA and protein expressions in offspring from dams fed with high-calorie diet at weaning age. We further found that maternal high-calorie diet feeding significantly decreased Abca1 methylation level in offspring, with lower methylation levels of both CpG 11 and CpG 22 sites. Interestingly, we found that Abca1 methylation level was negatively associated with hepatic Abca1 mRNA expression in offspring from dams fed with high-calorie diet and controls. However, the expressions of key genes associated with hepatic cholesterol metabolism were not significant between fetuses of dams fed with high-calorie diet and control diet. In conclusion, our results indicate that maternal high-calorie diet feeding results in aberrant lipid metabolism, including hypercholesterolemia and fat deposits in the liver of offspring as early as weaning age. Furthermore, maternal high-calorie feeding can program hepatic cholesterol metabolism and Abca1 methylation in the early life of offspring.

Paternal cadmium exposure affects estradiol synthesis by impairing intracellular cholesterol homeostasis and mitochondrial function in offspring female mice

Cadmium (Cd) is a toxic heavy metal commonly found in nature and an endocrine disrupting chemical (EDC). Previous studies found that Cd can damage several organs, including the kidneys, bones, cardiovascular system and reproductive system. However, the effect of paternal Cd exposure on the offspring is unclear. In this study, 1 mg/kg of cadmium chloride (CdCl2) was injected intraperitoneally every other day in 8-week-old C57BL/6 J male mice to study the effects on their female offspring. Our results showed an increase in body weight, water intake and food intake in F1 female mice from the Cd-exposed group. The development of secondary follicles and antral follicles in the ovaries of Cd-treated was inhibited. Serum estradiol (E2) was found to be decreased. Further analysis revealed significant downregulation of StAR, P450scc, 17β-HSD, CYP17A1 and CYP19A1, which are related to E2 synthesis. Serum total cholesterol was increased and free cholesterol was reduced. Total cholesterol in ovarian tissue was decreased. qRT-PCR and Western blot analysis revealed a decrease in the mRNA and protein expression of HMGCR, LDLR, and ABCA1, which are associated with cholesterol homeostasis. Oil red O staining indicated that lipid droplets (LDs) were accumulated in ovarian tissues, while the expression of ATGL and HSL proteins associated with lipid droplet degradation was significantly downregulated. In juvenile female mice, ultrastructural alterations of mitochondria in the ovaries were observed by transmission electron microscopy (TEM). In adult female mice, the expression of proteins associated with mitochondrial dynamics (DRP1 and MFN2) was significantly reduced in the ovaries. Overall, our study suggests that paternal Cd exposure inhibits follicular development, and affects serum E2 synthesis by impairing cholesterol homeostasis and affecting mitochondrial function.

Effects of liposoluble components of highland barley spent grains on physiological indexes, intestinal microorganisms, and the liver transcriptome in mice fed a high-fat diet.

The purpose of this study was to investigate the effects of the active ingredients of barley lees on the physiological indexes, intestinal flora, and liver transcriptome of mice fed a high-fat diet. Twenty-four male C57BL/6J mice were randomly divided into 4 groups and fed the experimental diets for 5 weeks. The results showed that the fat-soluble components of distillers' grains significantly reduced body weight, abdominal fat, perirenal fat, blood glucose, low-density lipoprotein cholesterol, triglycerides, and total cholesterol in the high-fat diet-fed mice (p < .05), significantly decreased alanine aminotransferase and malondialdehyde levels, and significantly increased total superoxide dismutase, catalase, reduced glutathione and glutathione peroxidase levels (p < .05). At the phylum level, lipid-soluble components significantly increased the abundance of Bacteroidetes and decreased the Firmicutes/Bacteroidetes ratio. At the genus level, the relative abundances of Bacteroidetes and Clostridium were increased. Transcriptomic analysis showed that lipid-soluble components of spent grains reduced the mRNA expression of ANGPTL8, CD36, PLTP, and SOAT1 and increased the mRNA expression of CYP7A1 and ABCA1 in the cholesterol metabolism pathway, promoted the transport of cholesterol, and inhibited the absorption of cholesterol, which can decrease cholesterol levels by speeding up the conversion of cholesterol into bile acids.

Huazhuotongmai decoction exerts anti-atherosclerotic effects by modulating the expression of ABCA1/SR-B1/PPAR-γ in vivo and in vitro

BackgroundPrevious studies have suggested that treatment with Chinese herbs has a protective effect on atherosclerosis (AS). This study aims to explore the effect mechanism of Huazhuotongmai(HZTM) on AS from the perspective of reverse cholesterol transport in vivo and in vitro. MethodsUltra high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-Q/TOF MS) was used to identify and analyzed the main chemical compounds from HZTM. Foam cells were induced with oxidized low-density lipoprotein at 80 μg/ml. The change in cholesterol and expressions of inflammatory factors including TNF-α, IL-6 and ICAM-1 were observed after HZTM treatment. In vivo, HE staining was applied to observe the morphological changes in the thoracic aorta. The serum lipid level was measured by an automatic biochemical analyzer. RT-PCR and Western blot were applied to detect the mRNA and protein expression of ABCA1, SR-BI or PPAR-γ both in vivo and in vitro. ResultsA total of 30 compounds were identified in HZTM water solution. The HZTM significantly reduced the content of cholesterol ester and total cholesterol, and decreased the expressions of TNF-α, IL-6 and ICAM-1 (all P < 0.05) in foam cells. In vivo, HE staining showed HZTM restored the damage of the aortic intima and decreases the triglyceride and low-density lipoprotein cholesterol content (P < 0.05). RT-PCR and Western blot showed that the expressions of ABCA1, SR-BI or PPAR-γ in the high-dose HZTM group were higher than those in the model group (P < 0.05). ConclusionOur study indicated that HZTM decoction could show anti-atherosclerotic effects by modulating the expressions of ABCA1, SR-BI and PPAR-γ.

Combined with UPLC-Triple-TOF/MS-based plasma lipidomics and molecular pharmacology reveals the mechanisms of schisandrin against Alzheimer’s disease

BackgroundAlzheimer’s disease (AD), a type of neurodegeneration disease, is characterized by Aβ deposition and tangles of nerve fibers. Schisandrin is one of the main components of Fructus Schisandrae Chinensis. Researches showed that schisandrin can improve the cognitive impairment and memory of AD mice, but the specific mechanism has not been fully elucidated.PurposeThe purpose of this study is to investigate the possible mechanism of schisandrin in improving AD pathology.MethodsThe Morris water maze test was executed to detect spatial learning and memory. Ultra performance liquid chromatography-Triple time of flight mass spectrometry (UPLC-Triple-TOF/MS)-based plasma lipidomics was used to study the changes of plasma lipids. Moreover, we measured the levels of protein and mRNA expression of APOE and ABCA1 in the rat brains and in BV2 microglia.ResultsOur study found that schisandrin could improve learning and memory, and reduce Aβ deposition in AD rats. Furthermore, we found that schisandrin can improve plasma lipid metabolism disorders. Therefore, we hypothesized schisandrin might act via LXR and the docking results showed that schisandrin interacts with LXRβ. Further, we found schisandrin increased the protein and mRNA expression of LXR target genes APOE and ABCA1 in the brain of AD rats and in BV2 microglia.ConclusionOur study reveals the neuroprotective effect and mechanism of schisandrin improves AD pathology by activating LXR to produce APOE and ABCA1.

214-OR: Effects of Polyphenols on Cholesterol Efflux and Insulin Secretion in MIN6 Cells

Background: Diabetic dyslipidemia is characterized by elevated levels of triglyceride-rich lipoproteins and reduced levels of HDL-cholesterol (HDL-C) . Low levels of HDL-C are associated with an increased risk of atherosclerotic cardiovascular disease, because HDL protects against atherosclerosis through multiple mechanisms include removal of excess cholesterol from macrophages. HDL can also influence cholesterol homeostasis in pancreatic β-cell. It is noteworthy that absence of ATP-binding cassette transporter A1 (ABCA1) , which is a cellular cholesterol transporter and regulates islet cholesterol efflux, results in islet cholesterol overload and impaired insulin release in mice. We examined the associations of cholesterol efflux and insulin secretion in MIN6 cells with polyphenols that is reported to increase cholesterol efflux. Methods: Murine MIN6 cells were labeled with 3H-cholesterol and incubated with ApoA1 (μg/ml) or HDL (25 μg/ml) for 24 hours. The percentage cholesterol efflux was calculated by dividing the media-derived radioactivity by the sum of the radioactivity in the media and the cells. The effect of polyphenols on the cholesterol efflux was studied, adding that into the medium before the analysis of the cholesterol efflux. Insulin secretion was assessed by ELISA as the concentration of insulin in the culture medium. The mRNA expression of ABCA1 and ABCG1 were determined by real-time Quantitative RT-PCR. Results: Under the existence of polyphenols (isorhamnetin) , the ApoA1 or HDL-mediated cholesterol efflux had significantly increased by 1.4% or 1.8%, respectively (n=4, p&amp;lt;0.01) . Isorhamnetin had increased insulin secretion by 882 ng/mg protein/h (n=3, p&amp;lt;0.05) and significantly decreased ABCA1 and ABCG1 expressions. Conclusion: These data suggest that isorhamnetin increases cholesterol efflux and insulin secretion in MIN6 cells. Isorhamnetin could be the interesting candidate to investigate the new treatment for patients with diabetes mellitus. Disclosure K.Matsuki: None. Y.Kimura: None. K.Matsumura: None. J.Tanabe: None. H.Murakami: None. M.Daimon: None. Funding JSPS KAKENHI Grant Number 20K11549

Expression of ABC transporters during syncytialization in preeclampsia.

Preeclampsia complicates 2-8% of pregnancies and is associated with prematurity and intrauterine growth restriction. Cholesterol and sterol transport is a key function of the placenta and it is elicited through ATP binding cassette (ABC) transporters. ABCA1 expression changes during trophoblast cell fusion, a process required to form the placental syncytium that enables maternal-fetal nutrient transfer. ABCA1 expression is dysregulated in preeclamptic placentas. But whether ABC transporters expression during trophoblast fusion is disrupted in preeclampsia remains unknown. We investigated if cholesterol and sterol ABC transporters are altered in term and preterm preeclampsia placentas and during human cytotrophoblast syncytialization. Human placental biopsies were collected from healthy term (≥37weeks; n=11) and term preeclamptic (≥36 6/7 weeks; n=8) and pre-term preeclamptic (28-35weeks; n=8) pregnancies. Both, protein and mRNA expression for ABCA1, ABCG1, ABCG5, and ABCG8 were evaluated. Primary cytotrophoblasts isolated from a subset of placentas were induced to syncytialize for 96h and ABCA1, ABCG1 and ABCG8 mRNA expression evaluated at 0h and 96h. Protein and gene expression of ABC transporters were not altered in preeclamptic placentas. In the healthy Term group, ABCA1 expression was similar before and after syncytialization. After 96h of syncytialization, mRNA expression of ABCA1 and ABCG1 increased significantly, while ABCG8 decreased significantly in term-preeclampsia, but not pre-term preeclampsia. While placental expression of ABCA1 and ABCG1 remained unaltered in term preeclampsia, the disruption in their dynamic expression pattern during cytotrophoblast syncytialization suggests that cholesterol transport may contribute to the pathophysiologic role of the placenta in preeclampsia.

AICAR upregulates ABCA1/ABCG1 expression in the retinal pigment epithelium and reduces Bruch's membrane lipid deposit in ApoE deficient mice

The etiology of age-related macular degeneration (AMD) is diverse; however, recent evidence suggests that the lipid metabolism-cholesterol pathway might be associated with the pathophysiology of AMD. The ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are essential for the formation of high-density lipoprotein (HDL) and the regulation of macrophage cholesterol efflux. The failure of retinal or retinal pigment epithelium (RPE) cholesterol efflux to remove excess intracellular lipids causes morphological and functional damage to the retina. In this study, we investigated whether treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMP-activated protein kinase (AMPK) activator, improves RPE cholesterol efflux and Bruch's membrane (BM) lipid deposits. The protein and mRNA levels of ABCA1 and ABCG1 in ARPE-19 cells and retinal and RPE/choroid tissue from apolipoprotein E-deficient (ApoE-/-) mice were evaluated after 24 weeks of AICAR treatment. The cholesterol efflux capacity of ARPE-19 cells and the cholesterol-accepting capacity of apoB-depleted serum from mice were measured. The thickness of the BM and the degree of lipid deposition were evaluated using electron microscopy. AICAR treatment increased the phosphorylation of AMPK and the protein and mRNA expression of ABCA1 and ABCG1 in vitro. It promoted cholesterol efflux from ARPE-19 cells and upregulated the protein and mRNA levels of ABCA1 and ABCG1 in the retina and RPE in vivo. ApoB-depleted serum from the AICAR-treated group showed enhanced cholesterol-accepting capacity. Long-term treatment with AICAR reduced BM thickening and lipid deposition in ApoE-/- mice. In conclusion, AICAR treatment increased the expression of lipid transporters in the retina and RPE in vivo, facilitated intracellular cholesterol efflux from the RPE in vitro, and improved the functionality of HDL to accept cholesterol effluxed from the cell, possibly via AMPK activation. Collectively, these effects might contribute to the improvement of early age-related pathologic changes in the BM. Pharmacological improvement of RPE cholesterol efflux via AMPK activation may be a potential treatment strategy for AMD.

Radiation-Induced Bystander Effects of Adipose-Derived Mesenchymal Stem Cells.

ObjectiveThe interaction of tumor cells with surrounding stem cells such as adipose-derived mesenchymal stem cells (ASCs) would be a crucial mechanism of tumor progression. It has been shown that irradiation can affect tumor microenvironment through different mechanisms. Given that, we aimed to examine the bystander radiation-induced effects of ASCs on different cancer cell lines.Materials and MethodsIn this experimental study, ASCs were extracted from five healthy donors, cultured and then irradiated with a 5Gy of gamma radiation. Following 72 hours of incubation, irradiated ASCs-conditioned media (IACM) and non-irradiated ASCs-conditioned media (NIACM) were collected. Following incubation of different cell lines, Jurkat, LNCaP, U87-MG, MDA-MB-231 and MCF-7, in different media, DMEM, NIACM, and IACM, ALDEFLUOR assay and wound healing assays, were conducted. Using quantitative real-time polymerase chain reaction (qRT-PCR), the expression of ATP-binding cassette transporter genes, ABCA1 and ABCG2, was measured in these cell lines. ResultsNIACM significantly increased ALDH activity in MDA-MB-231 cell (P=0.02), while IACM was associated with significant decrease in the LNCaP and MCF-7 cell lines, respectively P=0.02, P=0.03, compared to DMEM as the control. The area of the scratch site was significantly reduced in MDA-MB-231 cells cultured with NIACM compared to DMEM (P=0.04). Furthermore, ABCA1 mRNA expression was considerably decreased in IACM- but not in DMEMtreated LNCaP line (P=0.01).ConclusionIt seems, after exposing to radiation, ASCs modify to prevent tumor development and metastasis through their radiation-induced bystander effects. Therefore, a better understanding of ASCs function in the tumor microenvironment may provide new insights into therapeutic strategies to surmount radio-resistance in cancer treatment.

HDL Improves Cholesterol and Glucose Homeostasis and Reduces Atherosclerosis in Diabetes-Associated Atherosclerosis.

Background and Aims Apolipoprotein A-I (ApoA-I), the main component of high-density lipoprotein (HDL), not only promotes reverse cholesterol transport (RCT) in atherosclerosis but also increases insulin secretion in pancreatic β-cells, suggesting that interventions which raise HDL levels may be beneficial in diabetes-associated cardiovascular disease (CVD). Previously, we showed that TNF-related apoptosis-inducing ligand (TRAIL) deletion in Apolipoprotein Eknockout (Apoe−/−) mice results in diabetes-accelerated atherosclerosis in response to a “Western” diet. Here, we sought to identify whether reconstituted HDL (rHDL) could improve features of diabetes-associated CVD in Trail−/−Apoe−/− mice. Methods and Results Trail−/−Apoe−/− and Apoe−/− mice on a “Western” diet for 12 weeks received 3 weekly infusions of either PBS (vehicle) or rHDL (containing ApoA-I (20 mg/kg) and 1-palmitoyl-2-linoleoyl phosphatidylcholine). Administration of rHDL reduced total plasma cholesterol, triglyceride, and glucose levels in Trail−/−Apoe−/− but not in Apoe−/− mice, with no change in weight gain observed. rHDL treatment also improved glucose clearance in response to insulin and glucose tolerance tests. Immunohistological analysis of pancreata revealed increased insulin expression/production and a reduction in macrophage infiltration in mice with TRAIL deletion. Furthermore, atherosclerotic plaque size in Trail−/−Apoe−/− mice was significantly reduced associating with increased expression of the M2 macrophage marker CD206, suggesting HDL's involvement in the polarization of macrophages. rHDL also increased vascular mRNA expression of RCT transporters, ABCA1 and ABCG1, in Trail−/−Apoe−/− but not in Apoe−/− mice. Conclusions. rHDL improves features of diabetes-associated atherosclerosis in mice. These findings support the therapeutic potential of rHDL in the treatment of atherosclerosis and associated diabetic complications. More studies are warranted to understand rHDL's mechanism of action.

Liver X Receptor Exerts Anti-Inflammatory Effects in Colonic Epithelial Cells via ABCA1 and Its Expression Is Decreased in Human and Experimental Inflammatory Bowel Disease.

Liver X receptor (LXR) exerts anti-inflammatory effects in macrophages. The aim of this study was to explore the expression and function of LXR in the colonic epithelium under inflammatory conditions. The expression of LXR was explored by Western blot and immunohistochemistry in colonic biopsies from patients diagnosed with inflammatory bowel disease (IBD) and control patients. In addition, LXR and its target gene expression were analyzed in the colon from interleukin (IL)-10-deficient (IL-10-/-) and wild-type mice. Caco-2 cells were pretreated with the synthetic LXR agonist GW3965 and further challenged with IL-1β, the expression of IL-8 and chemokine (C-C motif) ligand (CCL)-28 chemokines, the activation of mitogen-activated protein (MAP) kinases, and the nuclear translocation of the p65 subunit of nuclear factor kappa B was evaluated. Glibenclamide was used as an ABCA1 antagonist. We found that LXR expression was downregulated in colonic samples from patients with IBD and IL-10-/- mice. The nuclear positivity of LXR inversely correlated with ulcerative colitis histologic activity. Colonic IL-1β mRNA levels negatively correlated with both LXRα and LXRβ in the colon of IL-10-/- mice, where a decreased mRNA expression of the LXR target genes ABCA1 and FAS was shown. In addition, IL-1β decreased the expression of the LXR target gene ABCA1 in cultured intestinal epithelial cells. The synthetic LXR agonist GW3965 led to a decreased nuclear positivity of the p65 subunit of nuclear factor kappa B, a phosphorylation ratio of the p44-42 MAP kinase, and the expression of CCL-28 and IL-8 in IL-1β-stimulated Caco-2 cells. The pharmacological inhibition of ABCA1 increased the phosphorylation of p44-42 after GW3965 treatment and IL-1β stimulation. The LXR-ABCA1 pathway exerts anti-inflammatory effects in intestinal epithelial cells and is impaired in the colonic mucosa of patients with IBD and IL-10-/- mice.

Testosterone stimulates cholesterol clearance from human macrophages by activating LXRα

AimsLow testosterone in men is associated with increased cardiovascular events and mortality. Testosterone has beneficial effects on several cardiovascular risk factors including cholesterol, endothelial dysfunction and inflammation as key mediators of atherosclerosis. Although evidence suggests testosterone is anti-atherogenic, its mechanism of action is unknown. The present study investigates whether testosterone exerts anti-atherogenic effects by stimulating cholesterol clearance from macrophages via activation of liver X receptor (LXRα), a nuclear master regulator of cellular cholesterol homeostasis, lipid regulation, and inflammation. Main methodsUsing human monocyte THP-1 cells differentiated into macrophages, the effect of testosterone (1–10 nM) treatment (24–72 h) on the expression of LXRα and LXR- targets apolipoprotein E (APOE), ATP-binding cassette transporter A1 (ABCA1), sterol regulatory element-binding transcription factor 1 (SREBF1) and fatty acid synthase (FAS), was investigated via qPCR and western blotting, with or without androgen receptor blockade with flutamide or LXR antagonism with CPPSS-50. Cholesterol clearance was measured by monitoring fluorescent dehydroergosterol (DHE) cellular clearance and ABCA1 cellular translocation was observed via immunocytochemistry in testosterone treated macrophages. Key findingsTestosterone increased mRNA and protein expression of LXRα, APOE, ABCA1, SREBF1 and FAS. These effects were blocked by flutamide and independently by LXR antagonism with CPPSS-50. Furthermore testosterone stimulated cholesterol clearance from the macrophages and promoted the translocation of ABCA1 toward the cell membrane. SignificanceTestosterone acts via androgen receptor-dependent pathways to stimulate LXRα and downstream targets to induce cholesterol clearance in human macrophages. This may, in part, explain the anti-atherogenic effects of testosterone frequently seen clinically.