One in 4 Americans >40 years of age takes a statin to reduce the risk of myocardial infarction, ischemic stroke, and other complications of atherosclerotic disease. The most effective statins produce a mean reduction in low-density lipoprotein cholesterol of 55% to 60% at the maximum dosage, and 6 of the 7 marketed statins are available in generic form, which makes them affordable for most patients. Primarily using data from randomized controlled trials, supplemented with observational data where necessary, this scientific statement provides a comprehensive review of statin safety and tolerability. The review covers the general patient population, as well as demographic subgroups, including the elderly, children, pregnant women, East Asians, and patients with specific conditions such as chronic disease of the kidney and liver, human immunodeficiency viral infection, and organ transplants. The risk of statin-induced serious muscle injury, including rhabdomyolysis, is <0.1%, and the risk of serious hepatotoxicity is ≈0.001%. The risk of statin-induced newly diagnosed diabetes mellitus is ≈0.2% per year of treatment, depending on the underlying risk of diabetes mellitus in the population studied. In patients with cerebrovascular disease, statins possibly increase the risk of hemorrhagic stroke; however, they clearly produce a greater reduction in the risk of atherothrombotic stroke and thus total stroke, as well as other cardiovascular events. There is no convincing evidence for a causal relationship between statins and cancer, cataracts, cognitive dysfunction, peripheral neuropathy, erectile dysfunction, or tendonitis. In US clinical practices, roughly 10% of patients stop taking a statin because of subjective complaints, most commonly muscle symptoms without raised creatine kinase. In contrast, in randomized clinical trials, the difference in the incidence of muscle symptoms without significantly raised creatine kinase in statin-treated compared with placebo-treated participants is <1%, and it is even smaller (0.1%) for patients who discontinued treatment because of such muscle symptoms. This suggests that muscle symptoms are usually not caused by pharmacological effects of the statin. Restarting statin therapy in these patients can be challenging, but it is important, especially in patients at high risk of cardiovascular events, for whom prevention of these events is a priority. Overall, in patients for whom statin treatment is recommended by current guidelines, the benefits greatly outweigh the risks.
Diabetes in humans accelerates cardiovascular disease caused by atherosclerosis. The relative contributions of hyperglycemia and dyslipidemia to atherosclerosis in patients with diabetes are not clear, largely because there is a lack of suitable animal models. We therefore have developed a transgenic mouse model that closely mimics atherosclerosis in humans with type 1 diabetes by breeding low-density lipoprotein receptor-deficient mice with transgenic mice in which type 1 diabetes can be induced at will. These mice express a viral protein under control of the insulin promoter and, when infected by the virus, develop an autoimmune attack on the insulin-producing β cells and subsequently develop type 1 diabetes. When these mice are fed a cholesterol-free diet, diabetes, in the absence of associated lipid abnormalities, causes both accelerated lesion initiation and increased arterial macrophage accumulation. When diabetic mice are fed cholesterol-rich diets, on the other hand, they develop severe hypertriglyceridemia and advanced lesions, characterized by extensive intralesional hemorrhage. This progression to advanced lesions is largely dependent on diabetes-induced dyslipidemia, because hyperlipidemic diabetic and nondiabetic mice with similar plasma cholesterol levels show a similar extent of atherosclerosis. Thus, diabetes and diabetes-associated lipid abnormalities have distinct effects on initiation and progression of atherosclerotic lesions.
Abstract-The "response-to-retention" hypothesis of atherogenesis states that atherogenic lipoproteins, such as low density lipoprotein (LDL), are retained in vessels by proteoglycans and undergo proatherosclerotic modifications. Transforming growth factor (TGF)-1 has been identified in atherosclerotic vessels and has been shown to stimulate the synthesis of chondroitin sulfate-and dermatan sulfate-containing proteoglycans by arterial smooth muscle cells (ASMCs), but whether it promotes lipid retention has not been addressed. We investigated whether TGF-1 modulates the biosynthesis of proteoglycans by ASMCs in a manner that promotes binding to LDL. Proteoglycans isolated from TGF-1-treated ASMCs exhibited enhanced binding to native LDL compared with the binding of proteoglycans isolated from control cultures (K d 18 g/mL LDL versus 81 g/mL LDL, respectively). The increase in proteoglycan-LDL binding caused by TGF-1 could be attributed primarily to the glycosaminoglycan portion of the proteoglycans, since the glycosaminoglycan chains liberated from the core proteins of these proteoglycans synthesized in the presence of TGF-1 exhibited increased LDL binding as well. Furthermore, glycosaminoglycan chains initiated on xyloside (an initiator of glycosaminoglycan synthesis) in the presence of TGF-1 were longer and displayed enhanced binding to LDL compared with the LDL binding of xyloside-initiated glycosaminoglycan chains from control cultures. These results indicate that TGF-1 promotes LDL-proteoglycan interaction primarily by its effects on the glycosaminoglycan synthetic machinery of the ASMCs. Therefore, this study supports a proatherogenic role for TGF-1. Key Words: proteoglycans Ⅲ glycosaminoglycans Ⅲ smooth muscle cells Ⅲ transforming growth factor-1 Ⅲ lipoproteins C ardiovascular disease resulting from coronary artery atherosclerosis is the major cause of morbidity and mortality in industrialized countries. [1][2][3] The biochemical and metabolic mechanisms responsible for the initiation and progression of atherosclerosis are not fully understood. Retention of lipoproteins by extracellular matrix molecules in the vascular wall is believed to play an important role in atherogenesis. 4 -7 The "response-to-retention" hypothesis states that apoB-and apoE-containing lipoproteins bind to and are retained by vascular matrix molecules, particularly proteoglycans. 5 The interaction of proteoglycans and lipoproteins predominantly occurs as an ionic interaction between negatively charged residues on the proteoglycans and positively charged residues on the apoproteins or via bridging molecules such as apoE and lipoprotein lipase. The retention of lipoproteins is increased by measures that increase the number of negatively charged residues on the glycosaminoglycan chain, either by an increase in chain length or increases in the degree of sulfation (see reviews 4 -8 ).Transforming growth factor (TGF)-1 is a cytokine that is increased in atherogenesis and has been shown to promote atherosclerotic lesion formation...
Septic shock results from an uncontrolled inflammatory response, mediated primarily by LPS. Cholesterol transport plays an important role in the host response to LPS, as LPS is neutralized by lipoproteins and adrenal cholesterol uptake is required for antiinflammatory glucocorticoid synthesis. In this study, we show that scavenger receptor B-I (SR-BI), an HDL receptor that mediates HDL cholesterol ester uptake into cells, is required for the normal antiinflammatory response to LPS-induced endotoxic shock. Despite elevated plasma HDL levels, SR-BI-null mice displayed an uncontrollable inflammatory cytokine response and a markedly higher lethality rate than control mice in response to LPS. In addition, SR-BI-null mice showed a lack of inducible glucocorticoid synthesis in response to LPS, bacterial infection, stress, or ACTH. Glucocorticoid insufficiency in SR-BI-null mice was due to primary adrenal malfunction resulting from deficient cholesterol delivery from HDL. Furthermore, corticosterone supplementation decreased the sensitivity of SR-BI-null mice to LPS. Plasma from control and SR-BI-null mice exhibited a similar ability to neutralize LPS, whereas SR-BI-null mice showed decreased plasma clearance of LPS into the liver and hepatocytes compared with normal mice. We conclude that SR-BI in mice is required for the antiinflammatory response to LPS-induced endotoxic shock, likely through its essential role in facilitating glucocorticoid production and LPS hepatic clearance.
Objective-The purpose of this study was to examine the interactive action of serum amyloid A (SAA), group IIA secretory phospholipase A 2 (sPLA 2 -IIA), and cholesteryl ester transfer protein (CETP) on HDL remodeling and cholesterol efflux during the acute phase (AP) response elicited in humans after cardiac surgery. Methods and Results-Plasma was collected from patients before (pre-AP), 24 hours after (AP-1 d), and 5 days after cardiac surgery (AP-5 d). SAA levels were increased 16-fold in AP-1 d samples. Key Words: SAA Ⅲ HDL Ⅲ CETP Ⅲ apoA-I Ⅲ inflammation I nflammation induces major changes in HDL levels and composition. Mediators of inflammation such as tumor necrosis factor (TNF)-␣ and interleukin (IL)-6 induce expression of serum amyloid A 1 and group IIA secretory phospholipase A 2 (sPLA 2 -IIA), 2 which dramatically alter HDL apolipoprotein content and levels, respectively. Acute phase SAA in the plasma is associated with HDL, where it can comprise the major apolipoprotein. 3 The increase in sPLA 2 -IIA activity results in hydrolysis of HDL surface phospholipids and a decrease in HDL particle size. 4 The plasma cholesteryl ester transfer protein (CETP) is an integral component of reverse cholesterol transport and regulates HDL cholesterol concentrations. By promoting the transfer of cholesteryl esters (CE) from HDL to apoB-containing lipoprotein particles, HDL-derived CE is taken up via the LDL receptor and cleared by the liver. 5 An additional result of CETP action is the generation of lipid-poor apoA-I, 6 a key acceptor in ATP-binding cassette transporter AI (ABCA1)-mediated lipid efflux. 7 The presence of SAA on HDL holds the potential to impact both the CE transfer and the apoA-I liberating ability of CETP. sPLA 2 -IIA could also impact the latter action of CETP as apoA-I was shown to dissociate more readily from CETP-remodeled reconstituted HDL after hydrolysis by bee venom phospholipase A 2 . 8 Given the centrality of inflammation in atherogenesis, there is a paucity of information regarding CETP function when acute phase HDL is the "substrate." In the present study, we used plasma from patients undergoing cardiac surgery with cardiopulmonary bypass as a "standardized" insult where the oxygenator membrane activates macrophages to produce cytokines. 9 We characterized the SAAcontaining acute phase (AP) HDL during the acute phase to define the polydisperse HDL "substrate" that CETP would encounter. We further investigated CETP function in the acute phase, particularly as it relates to the presence of SAA and sPLA 2 on AP HDL, with respect to its CE transfer and apoA-I liberating functions.Teleologically, the dramatic changes in HDL composition and metabolism during inflammation must serve a short-term purpose to allow the organism to survive a noxious assault. Acute tissue injury results in cell death with large quantities of cell membranes rich in phospholipids and cholesterol generated. Macrophages are mobilized to such sites, ingest these fragments, and acquire considerable lipid load. 10 We thus e...
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