RESUMEN
Treatment of dyslipidemia patients with lipid-lowering drugs leads to a significant reduction in low-density lipoproteins (LDL) level and a low to moderate level of increase in high-density lipoprotein (HDL) cholesterol in plasma. However, a possible role of these drugs in altering morphology and distribution of cholesterol particles is poorly understood. Here, we describe the in vitro evaluation of lipid-lowering drug effects in modulating morphological features of cholesterol particles using the plaque array method in combination with imaging flow cytometry. Image analyses of the cholesterol particles indicated that lovastatin, simvastatin, ezetimibe, and atorvastatin induce the formation of both globular and linear strand-shaped particles, whereas niacin, fibrates, fluvastatin, and rosuvastatin induce the formation of only globular-shaped particles. Next, purified very low-density lipoprotein (VLDL) and LDL particles incubated with these drugs showed changes in the morphology and image texture of cholesterol particles subpopulations. Furthermore, screening of 50 serum samples revealed the presence of a higher level of linear shaped HDL cholesterol particles in subjects with dyslipidemia (mean of 18.3%) compared to the age-matched normal (mean of 11.1%) samples. We also observed considerable variations in lipid-lowering drug effects on reducing linear shaped LDL and HDL cholesterol particles formation in serum samples. These findings indicate that lipid-lowering drugs, in addition to their cell-mediated hypolipidemic effects, may directly modulate morphology of cholesterol particles by a non-enzymatic mechanism of action. The outcomes of these results have potential to inform diagnosis of atherosclerosis and predict optimal lipid-lowering therapy.
Asunto(s)
Anticolesterolemiantes/uso terapéutico , Colesterol/sangre , Simvastatina/uso terapéutico , Anciano , Anticolesterolemiantes/farmacología , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Statin drugs are leading medication prescribed for treatment of dyslipidemic patients aimed at preventing both primary and secondary incidences of atherosclerosis-related cardiovascular events. Statin drugs competitively inhibit HMG-CoA reductase enzyme activity, thereby inhibiting cell-mediated cholesterol synthesis and reducing the low-density lipoprotein (LDL) cholesterol concentration of plasma. Conversely, the mechanism by which statins increase high-density lipoprotein (HDL) cholesterol concentration of plasma is not well understood. The plaque array method was used to examine the effect of statins on in vitro cholesterol particle formation. We observed that statins induced high-density cholesterol particle formation in buffer solution with or without the addition of human serum. Besides, simvastatin and lovastatin in their inactive pro-drug forms modulate formation of LDL and HDL cholesterol particles, indicating a novel nonenzymatic mechanism of statins. In a pilot study, screening of serum samples in the assay showed variation among patient samples in response to different statins. Specifically, screening of 50 serum samples with high cholesterol and statin treatment, compared with standard LDL-based measurement of statin efficacy, showed a good correlation for simvastatin (88%) and atorvastatin (84%). Taken together, our data indicate that statins, in addition to inhibiting enzyme-mediated cholesterol synthesis, have the capability to nonenzymatically modulate formation of LDL and HDL cholesterol particles in vitro. Similar interactions occurring in serum may provide a means to alter cholesterol particle formation in vivo.
Asunto(s)
HDL-Colesterol/efectos de los fármacos , LDL-Colesterol/efectos de los fármacos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Hipercolesterolemia/tratamiento farmacológico , Atorvastatina/farmacología , Colesterol/metabolismo , HDL-Colesterol/metabolismo , LDL-Colesterol/metabolismo , Citometría de Flujo , Humanos , Técnicas In Vitro , Lovastatina/farmacología , Proyectos Piloto , Profármacos/farmacología , Simvastatina/farmacologíaRESUMEN
BACKGROUND: Progressive accumulation of amyloid plaques in the regions of brain, carotid and cerebral arteries is the leading cause of Alzheimer's disease (AD) and related dementia in affected patients. The early identification of individuals with AD remains a challenging task relying on symptomatic events and thus the development of a biomarker-based approach will significantly aid in the diagnosis of AD. METHODS: Here we describe a flow cytometer-based serum biomarker identification method using plaque particles, and applying mass spectrometry based proteomic analysis of the isolated plaque particles for the identification of serum proteins present in the plaque particles. RESULTS: We identified 195 serum proteins that participate in the process of plaque particle formation. Among the 195 proteins identified, 68.2% of them overlapped in abeta-42, cholesterol, tau-275 and α-synuclein plaque particles. Significantly, 22.5% of the proteins identified as bound to abeta-42 plaque particles generated in AD serum were unique when compared with cholesterol, α-synuclein and tau plaque particles. In age-matched control experiments, 15% of them showed in vitro insoluble abeta-42 particle formation and 59% of the identified plaque particle constituents from AD serum were also present in the insoluble plaque particles derived from control. CONCLUSIONS: We have developed an in vitro method for plaque particle detection and identified serum protein markers that are associated with AD-related plaque particle formation. With further clinical validation, this assay may provide a novel, non-invasive means for the early detection of AD.