Modulation of Smooth Muscle Cell Migration by Members of the Low-Density Lipoprotein Receptor Family

ATHEROSCLEROTIC CARDIOVASCULAR DISEASE RISK ASSESSMENT: An American Society for Preventive Cardiology Clinical Practice Statement

Risk for atherosclerotic cardiovascular disease (ASCVD) shows considerable heterogeneity both in generally healthy persons and in those with known ASCVD. The foundation of preventive cardiology begins with assessing baseline ASCVD risk using global risk scores based on standard office-based measures. Persons at low risk are generally recommended for lifestyle management only and those at highest risk are recommended for both lifestyle and pharmacologic therapy. Additional “risk enhancing” factors, including both traditional risk factors and novel biomarkers and inflammatory factors can be used to further assess ASCVD risk, especially in those at borderline or intermediate risk. There are also female-specific risk enhancers, social determinants of health, and considerations for high-risk ethnic groups. Screening for subclinical atherosclerosis, especially with the use of coronary calcium screening, can further inform the treatment decision if uncertain based on the above strategies. Persons with pre-existing ASCVD also have variable risk, affected by the number of major ASCVD events, whether recurrent events have occurred recently, and the presence of other major risk factors or high-risk conditions. Current guidelines define high to very high risk ASCVD accordingly. Accurate ASCVD risk assessment is crucial for the appropriate targeting of preventive therapies to reduce ASCVD risk. Finally, the clinician-patient risk discussion focusing on lifestyle management and the risks and benefits of evidence-based pharmacologic therapies to best lower ASCVD risk is central to this process. This clinical practice statement provides the preventive cardiology specialist with guidance and tools for assessment of ASCVD risk with the goal of appropriately targeting treatment approaches for prevention of ASCVD events.

Levels of circulating soluble LR11, a regulator of smooth muscle cell migration, are highly associated with atherosclerotic plaques in patients with carotid artery stenosis

BACKGROUND

The levels of plasma sLR11, released from intimal SMCs, are positively associated with intima-media thickness (IMT) in asymptomatic subjects. We have evaluated the yet unknown pathological significance of sLR11 for plaque conditions in patients with carotid artery stenosis.

METHODS

The presence of LR11 in carotid plaques was investigated using autopsy specimens. A clinical ultrasonography study for elucidating relationships between sLR11 and plaque condition was performed in 46 patients.

RESULTS

Immunohistochemistry showed high levels of LR11 in SMCs within thickened intima and at the media-intima border of atherosclerotic carotid plaques. The levels of sLR11 in patients were clearly elevated compared to healthy controls. Univariate analysis of sLR11 revealed significant positive correlation with plaque score and a tendency to correlate with the stenotic fraction. Univariate and multiple regression analyses of plaque scores showed that sLR11, maximum IMT, and HDL-cholesterol independently determined plaque score. Finally, univariate analysis of initial sLR11 levels for changes in imaging markers after one-year follow-up showed that initial sLR11 levels significantly correlated with stenotic fraction progression.

CONCLUSIONS

The levels of sLR11, abundantly expressed in carotid atherosclerotic plaques, are highly associated with increased plaque score. sLR11 levels may be predictive of plaque conditions in patients with advanced carotid atherosclerosis.

Deletion of LR11 Attenuates Hypoxia-Induced Pulmonary Arterial Smooth Muscle Cell Proliferation With Medial Thickening in Mice

OBJECTIVE

We aimed to determine whether LR11 (low-density lipoprotein receptor with 11 binding repeats) is a potential key regulator of smooth muscle cell (SMC) proliferation during the progression of hypoxia-induced medial thickening in mice and whether sLR11 (soluble LR11) can serve as a biomarker in patients with pulmonary arterial hypertension.

APPROACH AND RESULTS

The role of LR11 in pulmonary arterial hypertension was investigated using mouse and cell models of induced hypoxia. The expression of LR11 and of hypoxia-inducible factor-1α was significantly increased in lung tissues from C57Bl/6 mice after 3 weeks of exposure to hypoxia compared with normoxia. Serum sLR11 levels were also increased. Physiological and histochemical analyses showed that increased right ventricular systolic pressure, right ventricular hypertrophy, and medial thickening induced under hypoxia in wild-type mice were attenuated in LR11(-/-) mice. The proliferation rates stimulated by hypoxia or platelet-derived growth factor-BB were attenuated in SMC derived from LR11(-/-) mice, compared with those from wild-type mice. Exogenous sLR11 protein increased the proliferation rates of SMC from wild-type mice. The expression of LR11 and hypoxia-inducible factor-1α was increased in cultured SMC under hypoxic conditions, and hypoxia-inducible factor-1α knockdown almost abolished the induction of LR11. Serum sLR11 levels were significantly higher in patients with, rather than without, pulmonary arterial hypertension. sLR11 levels positively correlated with pulmonary vascular resistance and mean pulmonary arterial pressure.

CONCLUSIONS

LR11 regulated SMC proliferation during the progression of hypoxia-induced medial thickening in mice. The findings obtained from mice, together with those in humans, indicate that sLR11 could serve as a novel biomarker that reflects the pathophysiology of proliferating medial SMC in pulmonary arterial hypertension.

Circulating soluble form of LR11, a regulator of smooth muscle cell migration, is a novel marker for intima-media thickness of carotid arteries in type 2 diabetes

BACKGROUND

Smooth muscle cell (SMC) migration from the media to the intima, a process affecting plaque stability in advanced-stage atherosclerosis, is under the control of LR11. To delineate the clinical significance of the circulating soluble form of LR11 (sLR11) in patients with type 2 diabetes (T2D), we analyzed the correlation of sLR11 levels with intima-media thickness (IMT) of carotid arteries.

METHODS

Plasma sLR11 levels were measured in 165 patients with T2D (mean age 56.2±10.4 y, 58.2% males, and BMI 24.6±3.6) by ELISA. Averaged IMT levels of common carotid arteries were determined by ultrasonography.

RESULTS

Circulating sLR11 levels were 9.8±3.5ng/ml, and correlated positively with the classical atherosclerosis risk factors age, sex, systolic blood pressure, low-density lipoprotein-cholesterol (LDL-C), fasting plasma-glucose (FPG), and glycosylated hemoglobin. Multivariate linear regression analysis indicated that only FPG was associated with sLR11; sLR11 correlated positively with IMT, together with age and FPG, but less with LDL-C. Among the serum risk factors for IMT, multivariate linear regression analysis uncovered that sLR11 was independently associated with IMT. Subsequent logistic analysis revealed that FPG correlated best with IMT values at a cut-off of 0.80mm and sLR11 at a cut-off of 0.90mm, respectively, while LDL-C showed lower discriminatory power at any IMT cut-off values.

CONCLUSION

Increased sLR11 concentrations are highly associated with increased IMT as well as with FPG in middle-aged, non-obese patients with T2D. Circulating sLR11 may be a novel marker representing the pathophysiology of intimal SMCs in patients with T2D.

Phenotypic transformation of smooth muscle cells from porcine coronary arteries is associated with connexin 43

The current study aimed to investigate the relevance of the gap junction protein connexin Cx43 in coronary artery smooth muscle cell (SMC) heterogeneity and coronary artery restenosis. SMCs were isolated from the coronary artery of 3‑month‑old pigs using enzymatic digestion. Two distinct SMC populations were isolated: Rhomboid (R) and spindle‑shaped (S) cells. S‑SMCs exhibited relatively lower rates of proliferation, exhibiting a classic ''hills‑and valleys'' growth pattern; R‑SMCs displayed increased proliferation rates, growing as mono‑ or multi‑layers. Immunofluorescent staining, polymerase chain reaction and western blotting were used to assess the expression of Cx40 and Cx43 in SMCs. For further evaluation, cultured SMCs were treated with 10 ng/ml platelet‑derived growth factor (PDGF)‑BB with or without the gap junction blocker 18α‑glycyrrhetinic acid. Stent‑induced restenosis was assessed in vivo. Different expression patterns were observed for Cx40 and Cx43 in R‑ and S‑SMCs. Cx40 was the most abundant Cx in S‑SMCs, whereas CX43 was identified at relatively higher levels than Cx40 in R‑SMCs. Notably, PDGF‑BB converted S‑SMCs to R‑SMCs, with increased Cx43 expression, while 18α‑glycyrrhetinic acid inhibited the PDGF‑BB‑induced phenotypic alterations in S‑SMCs. Additionally, restenosis was confirmed in pigs 1‑month subsequent to stent placement. R‑SMCs were the major cell population isolated from stent‑induced restenosis artery tissues, and exhibited markedly increased Cx43 expression, in accordance with the in vitro data described above. In conclusion, the phenotypic transformation of coronary artery SMCs is closely associated with Cx43, which is involved in restenosis. These observations provide a basis for the use of Cx43 as a novel target in restenosis prevention.

Levels of soluble LR11/SorLA are highly increased in the bile of patients with biliary tract and pancreatic cancers

BACKGROUND

The utility of molecules derived from cancer cells as biomarkers of the pathological status in biliary tract and pancreatic cancers is still limited. Soluble LDL receptor relative with 11 ligand-binding repeats (sLR11), a molecule released from immature cells, has been shown to be a circulating biomarker for early stage hematological malignancies.

METHODS

We have evaluated the pathological significance of bile sLR11 levels in 147 samples from 72 patients with biliary tract cancer (BTC), pancreatic cancer (PC), or benign diseases.

RESULTS

The bile sLR11 levels in the cancer patients were significantly increased compared with those in patients without cancer, independent of cytological detection of cancer cells in bile. The average bile sLR11 levels in cancer patients were significantly higher than in those with benign diseases, while levels of bile carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) were not different. LR11 protein was found to be highly expressed in the BTC and PC cells. The LR11 transcript levels in cholangiocarcinoma and pancreatic cancer cell lines were sharply induced during proliferation and significantly increased under hypoxic conditions.

CONCLUSIONS

Therefore, sLR11 levels in bile may be indicative of cancer cell conditions and may serve as potential novel biomarker in patients with BTC and PC.

Soluble LR11 is a novel biomarker for vascular lesions late after Kawasaki disease

OBJECTIVE

Coronary artery lesions (CALs) and a risk for early onset of atherosclerosis are major concerns following Kawasaki disease (KD). Intimal smooth muscle cells (SMCs) have an important role in vascular lesions in KD. It is known that soluble LR11 (sLR11) is a novel biomarker for vascular lesions and LR11 is markedly expressed in intimal SMCs in atherosclerotic lesions. In this study, we hypothesized that sLR11 reflects the presence of vascular lesions late after KD.

METHODS

Twenty-three age-matched controls (group 1) and 59 patients with a history of KD were enrolled; 36 with KD had normal coronary arteries or regressed aneurysms (group 2), and 23 had CALs (group 3).

RESULTS

Serum sLR11 levels in group 3 (median, interquartile range (IQR): 11.1 ng/mL, 9.3-13.9 ng/mL) were significantly higher than those in groups 1 (8.4 ng/mL, 7.1-10.2 ng/mL, p < 0.001) and 2 (9.0 ng/mL, 7.7-10.1 ng/mL, p < 0.01). Levels of sLR11 were positively correlated with levels of high-sensitivity C-reactive protein (r = 0.480, p < 0.01) and lipoprotein (a) (r = 0.486, p < 0.01).

CONCLUSION

These findings suggest that sLR11 reflects the development of vascular lesions in patients with serious CALs.

The rs1803274 polymorphism of the BCHE gene is associated with an increased risk of coronary in-stent restenosis

Background

We sought to identify gene polymorphisms that confer susceptibility to in-stent restenosis after coronary artery bare-metal stenting in a Central European population.

Methods

160 controls without post–percutaneous coronary intervention in-stent restenosis were matched for age, sex, vessel diameter, and diabetes to 160 consecutive cases involving in-stent restenosis of the target lesion within 12 months. Using real time polymerase chain reaction and melting-curve analysis, we detected 13 single-nucleotide polymorphisms in 11 candidate genes - rs1803274 (BCHE gene), rs529038 (ROS1), rs1050450 (GPX1), rs1800849 (UCP3), rs17216473 (ALOX5AP), rs7412, rs429358 (ApoE), rs2228570 (VDR), rs7041, rs4588 (GC), rs1799986 (LRP1) and rs2228671 (LDLR). Multivariable logistic regression was used to test for associations.

Results

The rs1803274 polymorphism of BCHE was significantly associated with in-stent restenosis (OR 1.934; 95 % CI: 1.181–3.166; p = 0.009). No association was found with the other studied SNPs.

Conclusions

The A allele of rs1803274 represents a risk factor for in-stent restenosis in Central European patients after percutaneous coronary intervention with bare-metal stent implantation.

Circulating soluble LR11, a novel marker of smooth muscle cell proliferation, is enhanced after coronary stenting in response to vascular injury

OBJECTIVE

Restenosis after vascular intervention remains a major clinical problem. Circulating LR11 has been shown a novel marker of intimal smooth muscle cell (SMC) proliferation in human and animal studies. The present study was performed to clarify the clinical significance of circulating LR11 in patients with stable angina pectoris after coronary stenting.

METHODS AND RESULTS

We firstly investigated the circulating sLR11 levels for 28 days after arterial injury in mice, and then assessed time-dependent change in circulating sLR11 level after coronary stenting in a clinical study. Mouse sLR11 levels rapidly increased to 4.0-fold of the control value without cuff placement at postoperative day (POD) 14, and the levels gradually declined to 3.1-fold of the control value until POD 28 in mice. The circulating soluble LR11 levels were measured (before and at 14, 60 and 240 days after coronary stenting in a clinical study of 102 consecutive patients with stable angina pectoris who were treated with percutaneous coronary intervention. Circulating sLR11 levels were significantly increased on days 14 and 60 after the procedure and positively associated with the angiographic late loss index.

CONCLUSIONS

Our study suggested that circulating sLR11 levels may be a potential marker for angiographic late loss in patients after coronary stenting. Further mechanistic studies are expected to know the clinical significance of sLR11 as a novel marker for intimal SMC.

The soluble form of LR11 protein is a regulator of hypoxia-induced, urokinase-type plasminogen activator receptor (uPAR)-mediated adhesion of immature hematological cells

A key property of hematopoietic stem and progenitor cells (HSPCs) regarding differentiation from the self-renewing quiescent to the proliferating stage is their adhesion to the bone marrow (BM) niche. An important molecule involved in proliferation and pool size of HSPCs in the BM is the hypoxia-induced urokinase-type plasminogen activator receptor (uPAR). Here, we show that the soluble form (sLR11) of LR11 (also called SorLA or SORL1) modulates the uPAR-mediated attachment of HSPCs under hypoxic conditions. Immunohistochemical and mRNA expression analyses revealed that hypoxia increased LR11 expression in hematological c-Kit(+) Lin(-) cells. In U937 cells, hypoxia induced a transient rise in LR11 transcription, production of cellular protein, and release of sLR11. Attachment to stromal cells of c-Kit(+) Lin(-) cells of lr11(-/-) mice was reduced by hypoxia much more than of lr11(+/+) animals. sLR11 induced the adhesion of U937 and c-Kit(+) Lin(-) cells to stromal cells. Cell attachment was increased by sLR11 and reduced in the presence of anti-uPAR antibodies. Furthermore, the fraction of uPAR co-immunoprecipitated with LR11 in membrane extracts of U937 cells was increased by hypoxia. CoCl2, a chemical inducer of HIF-1α, enhanced the levels of LR11 and sLR11 in U937 cells. The decrease in hypoxia-induced attachment of HIF-1α-knockdown cells was largely prevented by exogenously added sLR11. Finally, hypoxia induced HIF-1α binding to a consensus binding site in the LR11 promoter. Thus, we conclude that sLR11 regulates the hypoxia-enhanced adhesion of HSPCs via an uPAR-mediated pathway that stabilizes the hematological pool size by controlling cell attachment to the BM niche.

Enhanced circulating soluble LR11 in patients with diabetic retinopathy

PURPOSE

To investigate the relationship of circulating levels of soluble form of LR11 (sLR11; also called SorLA or SORL1), with the progression of proliferative diabetic retinopathy (PDR) in patients with type 2 diabetes mellitus.

DESIGN

Cross-sectional study.

METHODS

Fifty-four patients with type 2 diabetes mellitus were divided into 2 sex- and age-matched groups: one with PDR (n = 29) and the other with nonproliferative diabetic retinopathy (n = 25). The serum sLR11 levels were measured with an immunodetection system followed by chemifluorescence quantification.

RESULTS

The serum sLR11 levels were higher in the PDR group than in the nonproliferative diabetic retinopathy group (5.8 ± 1.2 U vs 3.7 ± 1.3 U; P < .01). A multivariate regression analysis showed that circulating sLR11 is a factor contributing to the prediction of PDR independent of other classical risk factors, and an area under the receiver operating characteristic curve analysis revealed that the sensitivity and the specificity were equivalent to or more than those of other factors. Among the classical risk factors for PDR, glycosylated hemoglobin levels showed the highest correlation coefficient (P < .01) for the sLR11 concentrations.

CONCLUSIONS

Serum sLR11 concentration may reflect the progression of PDR in patients with type 2 diabetes mellitus. sLR11, released from immature vascular cells and indicating the development of atherosclerosis, is expected to be a novel candidate biomarker indicating diabetic retinopathy in patients with type 2 diabetes mellitus.

The absence of urokinase-type plasminogen activator receptor plays a role in the insulin-independent glucose metabolism

The urokinase-type plasminogen activator receptor (uPAR) is a glycosylphosphatidylinositol-anchored membrane protein with multiple functions. In the present study, we examined whether the uPAR plays any role in the regulation of glucose metabolism. The experiments were performed using male wild-type (uPAR) and uPAR knockout (uPAR) C57BL/6J mice. The blood glucose levels after the intraperitoneal injection of glucose were significantly decreased in uPAR mice compared with uPAR mice. On the other hand, there were no differences in the insulin secretion induced by glucose injection and the reactivity of insulin between uPAR and uPAR mice. The expression levels of glucose transporter 2 (GLUT2) in the liver and GLUT4 in the skeletal muscles from the uPAR mice were significantly increased compared with those of the uPAR mice. In addition, we found that the level of phosphorylation of AMP-activated protein kinase in skeletal muscles and myoblasts from the uPAR mice increased compared with those in uPAR mice. These data suggest that the increase in the GLUT2 and GLUT4 expression and the activation of AMP-activated protein kinase by uPAR deficiency enhances the glucose intake. These findings therefore provide new insights into the role of uPAR in the glucose metabolism.

Activation of intracellular signaling systems by high-density lipoproteins

The proteosome of high-density lipoprotein particles is quite complex and consists of up to 75 different proteins and enzymes. The specific protein cargo of HDL particles regulates their functionality. In addition to their documented capacity to engage in reverse cholesterol transport, reduce oxidized lipid, and function as apoprotein donors, HDL particles can activate a variety of signaling systems in endothelial cells, smooth muscle cells, and platelets. The HDLs can deliver sphingolipids to the surface of these cell types and activate sphingosine phosphate receptors. Sphingosine phosphate receptors are coupled to numerous different intracellular signaling cascades exerting roles in vasodilatation, inflammation, cell migration and apoptosis, inhibition of platelet activation, and endothelial adhesion molecule expression, among other functions. The ability of HDL to influence such a diverse array of cellular functions lends biological plausibility to the substantial epidemiological and clinical evidence suggesting that the HDLs are unique among lipoproteins in that they are vasculoprotective and antiatherogenic.

Development of an Immunoassay for the Quantification of Soluble LR11, a Circulating Marker of Atherosclerosis

Background: Vascular smooth muscle cells (SMCs) migrate from the arterial media to the intima in the progression of atherosclerosis, and dysfunction of SMCs leads to enhanced atherogenesis. A soluble form of the LDL receptor relative with 11 ligand-binding repeats (sLR11) is produced by the intimal SMCs, and the circulating concentrations of sLR11 likely reflect the pathophysiological condition of intimal SMCs. Furthermore, polymorphism of the LR11 gene has been found to be related to the onset of Alzheimer disease. This study describes the development of a sandwich immunoassay for quantifying sLR11 in human serum and cerebrospinal fluid.

Methods: We used synthetic peptides or DNA immunization to produce monoclonal antibodies (MAbs) A2-2–3, M3, and R14 against different epitopes of LR11.

Results: sLR11 was immunologically identified as a 250-kDa protein in human serum and cerebrospinal fluid by SDS-PAGE separation, and was purified from serum by use of a receptor-associated protein and MAb M3. An immunoassay for quantification of sLR11 with a working range of 0.25–4.0 μg/L was developed using the combination of MAbs M3 and R14. Treatment of serum with 5.25% n-nonanoyl-N-methyl-d-glucamine reduced the matrix effects of serum on the absorbance detection in the ELISA system. The linear dynamic range of the ELISA spanned the variation of circulating sLR11 concentrations in individuals with atherosclerosis.

Conclusions: A sandwich ELISA was established for quantifying sLR11 in serum and cerebrospinal fluid. This technique provides a novel means for assessing the pathophysiology of atherosclerosis, and possibly neurodegenerative diseases.

Ang II-stimulated migration of vascular smooth muscle cells is dependent on LR11 in mice

Medial-to-intimal migration of SMCs is critical to atherosclerotic plaque formation and remodeling of injured arteries. Considerable amounts of the shed soluble form of the LDL receptor relative LR11 (sLR11) produced by intimal SMCs enhance SMC migration in vitro via upregulation of urokinase-type plasminogen activator receptor (uPAR) expression. Here, we show that circulating sLR11 is a novel marker of carotid intima-media thickness (IMT) and that targeted disruption of the LR11 gene greatly reduces intimal thickening of arteries through attenuation of Ang II-induced migration of SMCs. Serum concentrations of sLR11 were positively correlated with IMT in dyslipidemic subjects, and multivariable regression analysis suggested sLR11 levels as an index of IMT, independent of classical atherosclerosis risk factors. In Lr11-/- mice, femoral artery intimal thickness after cuff placement was decreased, and Ang II-stimulated migration and attachment of SMCs from these mice were largely abolished. In isolated murine SMCs, sLR11 caused membrane ruffle formation via activation of focal adhesion kinase/ERK/Rac1 accompanied by complex formation between uPAR and integrin alphavbeta3, a process accelerated by Ang II. Overproduction of sLR11 decreased the sensitivity of Ang II-induced activation pathways to inhibition by an Ang II type 1 receptor blocker in mice. Thus, we demonstrate a requirement for sLR11 in Ang II-induced SMC migration and propose what we believe is a novel role for sLR11 as a biomarker of carotid IMT.

A Secreted Soluble Form of LR11, Specifically Expressed in Intimal Smooth Muscle Cells, Accelerates Formation of Lipid-Laden Macrophages

OBJECTIVE

Macrophages play a key role in lipid-rich unstable plaque formation and interact with intimal smooth muscle cells (SMCs) in early and progressive stages of atherosclerosis. LR11 (also called sorLA), a member of low-density lipoprotein receptor family, is highly and specifically expressed in intimal SMCs, and causes urokinase-type plasminogen activator receptor-mediated degradation of extracellular matrices. Here we investigated whether the secreted soluble form of LR11 (solLR11) enhances adhesion, migration, and lipid accumulation in macrophages using animal models and cultured systems.

METHODS AND RESULTS

Immunohistochemistry showed solLR11 expression in thickened intima of balloon-denuded rat artery. Macrophage infiltration into the cuff-injured artery was markedly reduced in LR11-deficient mice. In vitro functional assays using THP-1-derived macrophages showed that solLR11 (1 microg/mL) significantly increased acetylated low-density lipoprotein uptake by THP-1 cells and cell surface levels of scavenger receptor SR-A 1.7- and 2.8-fold, respectively. SolLR11 dose-dependently increased the migration activity of THP-1 macrophages and adhesion to extracellular matrices 2.0- and 2.1-fold, respectively, at 1 microg/mL. These effects of solLR11 were almost completely inhibited by a neutralizing anti-urokinase-type plasminogen activator receptor antibody.

CONCLUSION

SolLR11, secreted from intimal SMCs, regulates adhesion, migration, and lipid accumulation in macrophages through activation of urokinase-type plasminogen activator receptor. The formation of lipid-laden macrophages in atherosclerotic plaques possibly is regulated by SolLR11 of intimal SMCs.

Prevention of stroke and dementia by statin therapy: Experimental and clinical evidence of their pleiotropic effects

Stroke and dementia are major causes of disability in most countries. Epidemiological studies have demonstrated that statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are likely to reduce the risk for developing these formidable disorders. The favorable outcomes in statin users may be attributable to not only cholesterol-dependent actions, but also various cholesterol-independent actions called "pleiotropic effects." Several clinical trials have suggested that statins decrease the incidence of stroke, especially ischemic stroke. Statins improve endothelial function, inhibit platelet activation, reduce blood coagulability, and suppress inflammatory reactions, all of which may contribute to the beneficial effects of the therapy. Statins also reduce the risk of vasospasm caused by subarachnoid hemorrhage (SAH). In addition, statins might inhibit the development and progression of Alzheimer's disease (AD), the dominant type of dementia in most industrialized countries, upstream of the amyloid cascade. In vitro studies have shown that statins modulate the metabolism of the beta-amyloid precursor protein (APP) and reduce the extracellular level of its proteolytic product, amyloid-beta (Abeta). The aggregated Abeta is cytotoxic, leading to formation of neurofibrillary tangles and neuronal loss in the brain. Inflammatory processes are active in AD and may contribute significantly to AD pathology. We review the experimental background regarding the pleiotropic effects of statins and summarize clinical trials that examined the preventative effects of statin therapy on stroke and dementia. We include current trials in which statin therapy is initiated within 24 hr of onset of acute ischemic stroke.