Increased electronegativity of high-density lipoprotein in uremia patients impairs its functional properties and is associated with the risk of coronary artery disease.

BACKGROUND AND AIMS: Uremia patients have impaired high-density lipoprotein (HDL) function and a high risk of coronary artery disease (CAD). Increased lipoprotein electronegativity can compromise lipoprotein function, but the effect of increased HDL electronegativity on HDL function and its association with CAD in uremia patient are not clear. We aimed to assess HDL electronegativity and various properties of HDL in uremia patients and investigate whether electronegative HDL is a risk factor for CAD in these individuals.

METHODS: HDL from 60 uremia patients and 43 healthy controls was separated into 5 subfractions (H1H5) with increasing electronegativity by using anion-exchange chromatography. Lipoprotein content was analyzed by gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry. HDL anti-oxidant, anti-apoptosis and cholesterol efflux activities were examined by fluorescence-based assays.

RESULTS: The percentage of H5 HDL (H5%) was significantly higher in uremia patients than in controls (p < 0.001). The concentration of apolipoprotein (Apo) AI was lower and apolipoprotein modifications were more prevalent in uremia HDL subfractions than in control HDL subfractions. Carbamylation of ApoAI and ApoCIII was increased in more electronegative HDL subfractions from uremia patients. Anti-oxidant activity, anti-apoptotic activity, and cholesterol efflux capability were reduced in HDL subfractions from uremia patients when compared with control HDL subfractions. Multiple logistic regression analysis showed that H5% was associated with CAD risk in uremia patients.

CONCLUSIONS: In HDL of uremia patients, increased electronegativity is accompanied by compositional changes and impaired function. Our findings indicate that increased H5% is associated with increased CAD risk in uremia patients.