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HDL-apoA-I exchange: rapid detection and association with atherosclerosis.

Borja MS, Zhao L, Hammerson B, Tang C, Yang R, Carson N, Fernando G, Liu X, Budamagunta MS, Genest J, Shearer GC, Duclos F, Oda MN - PLoS ONE (2013)

Bottom Line: Chemical modification of apoA-I also impairs its ability to exchange on and off HDL, a critical process in reverse cholesterol transport.In this study, we developed a method using electron paramagnetic resonance spectroscopy (EPR) to quantify HDL-apoA-I exchange.Using this approach, we measured the degree of HDL-apoA-I exchange for HDL isolated from rabbits fed a high fat, high cholesterol diet, as well as human subjects with acute coronary syndrome and metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Children's Hospital Oakland Research Institute, Oakland, California, United States of America.

ABSTRACT
High density lipoprotein (HDL) cholesterol levels are associated with decreased risk of cardiovascular disease, but not all HDL are functionally equivalent. A primary determinant of HDL functional status is the conformational adaptability of its main protein component, apoA-I, an exchangeable apolipoprotein. Chemical modification of apoA-I, as may occur under conditions of inflammation or diabetes, can severely impair HDL function and is associated with the presence of cardiovascular disease. Chemical modification of apoA-I also impairs its ability to exchange on and off HDL, a critical process in reverse cholesterol transport. In this study, we developed a method using electron paramagnetic resonance spectroscopy (EPR) to quantify HDL-apoA-I exchange. Using this approach, we measured the degree of HDL-apoA-I exchange for HDL isolated from rabbits fed a high fat, high cholesterol diet, as well as human subjects with acute coronary syndrome and metabolic syndrome. We observed that HDL-apoA-I exchange was markedly reduced when atherosclerosis was present, or when the subject carries at least one risk factor of cardiovascular disease. These results show that HDL-apoA-I exchange is a clinically relevant measure of HDL function pertinent to cardiovascular disease.

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Representative EPR spectra of spin-labeled apoA-I probe added to human plasma.The spectrum of spin-labeled apoA-I in apoB depleted plasma from a healthy human donor at 6°C (blue line) is compared to the spectra after a 15 minute incubation at 37°C (red line). The maximal nitroxide spectral response is obtained from spin-labeled apoA-I in an extended lipid-bound conformation (orange line). Sample response was normalized between instruments using a proprietary internal standard. Sample response was calculated by subtracting the peak amplitude at 6°C from the amplitude at 37°C and dividing by the amplitude of the 100% response standard.
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pone-0071541-g002: Representative EPR spectra of spin-labeled apoA-I probe added to human plasma.The spectrum of spin-labeled apoA-I in apoB depleted plasma from a healthy human donor at 6°C (blue line) is compared to the spectra after a 15 minute incubation at 37°C (red line). The maximal nitroxide spectral response is obtained from spin-labeled apoA-I in an extended lipid-bound conformation (orange line). Sample response was normalized between instruments using a proprietary internal standard. Sample response was calculated by subtracting the peak amplitude at 6°C from the amplitude at 37°C and dividing by the amplitude of the 100% response standard.

Mentions: HAE was quantified by comparing the EPR peak amplitude of spin-labeled apoA-I in plasma at 6°C to that of spin-labeled apoA-I in plasma after a 15-minute incubation at 37°C (Figure 2). No further increases in nitroxide signal amplitude were observed when sample EPR spectra were monitored an additional 6 hours (data not shown), indicating that equilibrium between exogenous apoA-I and blood plasma HDL is achieved within 15 minutes. Additionally, we have determined that the rate and endpoint of HAE are highly correlated (data not shown). For the purposes of this manuscript, all HAE data were collected by endpoint analysis.


HDL-apoA-I exchange: rapid detection and association with atherosclerosis.

Borja MS, Zhao L, Hammerson B, Tang C, Yang R, Carson N, Fernando G, Liu X, Budamagunta MS, Genest J, Shearer GC, Duclos F, Oda MN - PLoS ONE (2013)

Representative EPR spectra of spin-labeled apoA-I probe added to human plasma.The spectrum of spin-labeled apoA-I in apoB depleted plasma from a healthy human donor at 6°C (blue line) is compared to the spectra after a 15 minute incubation at 37°C (red line). The maximal nitroxide spectral response is obtained from spin-labeled apoA-I in an extended lipid-bound conformation (orange line). Sample response was normalized between instruments using a proprietary internal standard. Sample response was calculated by subtracting the peak amplitude at 6°C from the amplitude at 37°C and dividing by the amplitude of the 100% response standard.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756009&req=5

pone-0071541-g002: Representative EPR spectra of spin-labeled apoA-I probe added to human plasma.The spectrum of spin-labeled apoA-I in apoB depleted plasma from a healthy human donor at 6°C (blue line) is compared to the spectra after a 15 minute incubation at 37°C (red line). The maximal nitroxide spectral response is obtained from spin-labeled apoA-I in an extended lipid-bound conformation (orange line). Sample response was normalized between instruments using a proprietary internal standard. Sample response was calculated by subtracting the peak amplitude at 6°C from the amplitude at 37°C and dividing by the amplitude of the 100% response standard.
Mentions: HAE was quantified by comparing the EPR peak amplitude of spin-labeled apoA-I in plasma at 6°C to that of spin-labeled apoA-I in plasma after a 15-minute incubation at 37°C (Figure 2). No further increases in nitroxide signal amplitude were observed when sample EPR spectra were monitored an additional 6 hours (data not shown), indicating that equilibrium between exogenous apoA-I and blood plasma HDL is achieved within 15 minutes. Additionally, we have determined that the rate and endpoint of HAE are highly correlated (data not shown). For the purposes of this manuscript, all HAE data were collected by endpoint analysis.

Bottom Line: Chemical modification of apoA-I also impairs its ability to exchange on and off HDL, a critical process in reverse cholesterol transport.In this study, we developed a method using electron paramagnetic resonance spectroscopy (EPR) to quantify HDL-apoA-I exchange.Using this approach, we measured the degree of HDL-apoA-I exchange for HDL isolated from rabbits fed a high fat, high cholesterol diet, as well as human subjects with acute coronary syndrome and metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Children's Hospital Oakland Research Institute, Oakland, California, United States of America.

ABSTRACT
High density lipoprotein (HDL) cholesterol levels are associated with decreased risk of cardiovascular disease, but not all HDL are functionally equivalent. A primary determinant of HDL functional status is the conformational adaptability of its main protein component, apoA-I, an exchangeable apolipoprotein. Chemical modification of apoA-I, as may occur under conditions of inflammation or diabetes, can severely impair HDL function and is associated with the presence of cardiovascular disease. Chemical modification of apoA-I also impairs its ability to exchange on and off HDL, a critical process in reverse cholesterol transport. In this study, we developed a method using electron paramagnetic resonance spectroscopy (EPR) to quantify HDL-apoA-I exchange. Using this approach, we measured the degree of HDL-apoA-I exchange for HDL isolated from rabbits fed a high fat, high cholesterol diet, as well as human subjects with acute coronary syndrome and metabolic syndrome. We observed that HDL-apoA-I exchange was markedly reduced when atherosclerosis was present, or when the subject carries at least one risk factor of cardiovascular disease. These results show that HDL-apoA-I exchange is a clinically relevant measure of HDL function pertinent to cardiovascular disease.

Show MeSH
Related in: MedlinePlus