The etiology of human female infertility is often uncertain. The sterility of high-density lipoprotein (HDL) receptor-negative (SR-BI(-/-)) female mice suggests a link between female infertility and abnormal lipoprotein metabolism. SR-BI(-/-) mice exhibit elevated plasma total cholesterol [with normal-sized and abnormally large HDL and high unesterified to total plasma cholesterol (UC:TC) ratio]. We explored the influence of hepatic SR-BI on female fertility by inducing hepatic SR-BI expression in SR-BI(-/-) animals by adenovirus transduction or stable transgenesis. For transgenes, we used both wild-type SR-BI and a double-point mutant, Q402R/Q418R (SR-BI-RR), which is unable to bind to and mediate lipid transfer from wild-type HDL normally, but retains virtually normal lipid transport activities with low-density lipoprotein. Essentially wild-type levels of hepatic SR-BI expression in SR-BI(-/-) mice restored to nearly normal the HDL size distribution and plasma UC:TC ratio, whereas approximately 7- to 40-fold overexpression dramatically lowered plasma TC and increased biliary cholesterol secretion. In contrast, SR-BI-RR overexpression had little effect on SR-BI(+/+) mice, but in SR-BI(-/-) mice, it substantially reduced levels of abnormally large HDL and normalized the UC:TC ratio. In all cases, hepatic transgenic expression restored female fertility. Overexpression in SR-BI(-/-) mice of lecithin:cholesterol acyl transferase, which esterifies plasma HDL cholesterol, did not normalize the UC:TC ratio, probably because the abnormal HDL was a poor substrate, and did not restore fertility. Thus, hepatic SR-BI-mediated lipoprotein metabolism influences murine female fertility, raising the possibility that dyslipidemia might contribute to human female infertility and that targeting lipoprotein metabolism might complement current assisted reproductive technologies.

Expression of inducible nitric oxide synthase (iNOS), which leads to the production of nitric oxide (NO), is stimulated by proinflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha). Here we report on the roles of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein (MAP) kinases in IL-1beta/TNF-alpha-induced iNOS expression in adult rat astroglia. Cytokine-induced increases in nitrite accumulation (an index of NO production) and iNOS expression were attenuated by inhibition of NF-kappaB with pyrrolidine dithiocarbamate (PDTC). Similar attenuation of these cytokine-induced responses was produced by inhibition of MAP kinase (MEK), the immediate upstream activator of Erk, using PD098,059. Combined treatment of astroglia with PDTC and PD098,059 completely abolished the cytokine-induced increases in iNOS expression and nitrite accumulation. By contrast, the selective p38 kinase inhibitor SB203,580 amplified the effects of IL-1beta/TNF-alpha on nitrite accumulation. In accordance with these findings, IL-1beta- and TNF-alpha-induced a time-dependent increase in Erk1/Erk2 activation. This cytokine action was completely abolished by PD098,059 but was not altered by PDTC. Finally, IL-1beta and TNF-alpha induced degradation of NF-kappaB's bound inhibitory protein, IkappaB-alpha, leading to translocation of NF-kappaB into the nucleus. IkappaB-alpha expression was not restored to control levels by inhibition of MEK. Furthermore, inhibition of MEK with PD098,059 did not alter IL-1beta- and TNF-alpha-induced expression of active NF-kappaB. The results demonstrate that autonomous Erk and NF-kappaB pathways mediate cytokine-induced increases in iNOS expression in astroglia.

Objective-SR-BI/apolipoprotein (apo) E double knockout (dKO) mice exhibit many features of human coronary heart disease (CHD), including occlusive coronary atherosclerosis, cardiac hypertrophy, myocardial infarctions, and premature death. Here we determined the effects on this pathology of hepatic lipase (HL) deficiency, which has been shown to significantly modulate atherosclerosis. Method and Results-The SR-BI/apoE/HL triple knockout (tKO) mice generated for this study lived significantly longer (37%) than corresponding dKO controls (average lifespans: 63.0Ϯ0.8 versus 46.0Ϯ0.3 days), despite their increased plasma cholesterol levels. At 6 weeks of age, compared with dKO mice, tKOs exhibited significantly less aortic root and coronary artery occlusive atherosclerosis, and improved cardiac structure and function. However, by 9 weeks of age the hearts of tKO mice exhibited lipid-rich coronary occlusions, myocardial infarctions, and cardiac dysfunction essentially identical to that of 6-week-old dKO mice. Conclusions-HL-deficiency delays the onset and/or progression of atherosclerosis via a SR-BI-independent mechanism.Extent of occlusive coronary arterial lesions was more closely associated with cardiac dysfunction and lifespan than the amount of aortic root atherosclerosis, suggesting that these occlusions in dKO mice are responsible for ischemia, myocardial infarctions, and premature death. Key Words: atherosclerosis Ⅲ hepatic lipase Ⅲ high density lipoprotein receptor Ⅲ myocardial infarction T hough apolipoprotein E (apoE) or low-density lipoprotein receptor (LDLR) knockout (KO) murine models of dyslipidemia are often used to study lipoprotein metabolism and atherosclerosis, 1 they usually do not exhibit spontaneous occlusive coronary artery disease, myocardial infarction (MI), cardiac dysfunction and premature death, hallmarks of human coronary heart disease (CHD). Double knockout (dKO) mice deficient in the high-density lipoprotein (HDL) receptor (scavenger receptor class B type I, SR-BI) and apoE exhibit extensive aortic sinus atherosclerosis (advanced plaques with fibrous caps 2 that contain macrophages [unpublished data, 2005]), occlusive coronary arterial atherosclerosis (cellular and acellular plaques containing lipid [including cholesterol clefts], collagen, and fibrin deposits 3 ), and acute CHD when young (4 to 6 weeks old). 2-4 At 6 weeks of age, dKO hearts exhibit multiple, large infarctions with extensive fibrosis around the ventricular outflow tract and patchy MIs in the apex, right ventricular wall and interventricular septum. 3 In addition, they are hypertrophic with LV dilation, and exhibit severe dysfunction, including multiple electrocardiographic (ECG) abnormalities (ST elevation and depression, anesthesia induced conductance abnormalities (eg, bradyarrhythmias, AV blocks)), a 70% reduction in ϮdP/dT, and 50% reduced ejection fraction. The dKO mice die between 5 and 8 weeks of age (mean 6 weeks). 2,3 Similarities between dKO and human CHD raised the possibility that these mice may help to ...

Objective-Scavenger receptor class B type I (SR-BI)/apolipoprotein E (apoE) double knockout (dKO) mice exhibit many features of human coronary heart disease (CHD), including occlusive coronary atherosclerosis, cardiac hypertrophy, myocardial infarctions, and premature death. Here we determined the influence of B and T lymphocytes, which can contribute to atherosclerosis, ischemia-reperfusion injury, and cardiomyocyte death, on pathology in dKO mice. Method and Results-The lymphocyte-deficient SR-BI/apoE/recombination activating gene 2 (RAG2) triple knockout mice and corresponding dKO controls generated for this study exhibited essentially identical lipid-rich coronary occlusions, myocardial infarctions, cardiac dysfunction, and premature death (average lifespans 41.6Ϯ0.6 and 42.0Ϯ0.5 days, respectively). Conclusions-B and T lymphocytes and associated immunoglobulin-mediated inflammation are not essential for the development and progression of CHD in dKO mice. Strikingly, the dKO mice bred for this study (mixed C57BL/6ϫSV129ϫBALB/c background; strain 2) compared with the previously described dKO mice (75:25 C57BL/6:SV129 background; strain 1) had a shorter mean lifespan and steeper survival curve, characteristics especially attractive for studying the effects of environmental, pharmacological, and genetic manipulations on cardiac pathophysiology. Key Words: atherosclerosis Ⅲ HDL receptor Ⅲ myocardial infarction Ⅲ RAG2 Ⅲ echocardiography M urine models of dyslipidemia, such as the apolipoprotein E (apoE) or low-density lipoprotein (LDL) receptor knockout (KO) mice, have been used extensively to study atherosclerosis. However, even when subjected to high-fat/highcholesterol diets, all but one of these hypercholesterolemia and atherosclerosis systems usually do not result in spontaneous development of occlusive coronary artery disease, myocardial infarction (MI), cardiac dysfunction, or the premature death that are hallmarks of human coronary heart disease (CHD). The exception, mice doubly deficient for the HDL receptor scavenger receptor class B type I (SR-BI) and apoE (double KO [dKO]) not only exhibit extensive aortic sinus and occlusive coronary arterial atherosclerosis (advanced plaques with fibrous caps, fibrin deposition, and cholesterol clefts), but they also experience severe CHD at a very young age (4 to 6 weeks). [1][2][3] The hearts of dKO mice are hypertrophic and exhibit left ventricular (LV) dilation and multiple, large MIs. Severe cardiac dysfunction is demonstrated by multiple ECG abnormalities (ST segment elevation and depression, anesthesia-induced conductance abnormalities [eg, bradyarrhythmias, atrioventricular blocks]), a 70% reduction in ϮdP/dT, and 50% reduced ejection fraction. The mice die between 5 and 8 weeks of age (mean 6 weeks). Thus, the many similarities in CHD of dKO mice and humans raised the possibility that these mice may help in the study of the pathophysiology of CHD and genetic, pharmacological, and environmental approaches for its prevention and treatment.B and T lymphocytes ...