Determination of myeloperoxidase-induced apoAI-apoAII heterodimers in high-density lipoprotein.

Myeloperoxidase secreted by macrophages and neutrophils in atherosclerotic lesions generates a tyrosyl radical in apolipoprotein (apo) AI, a major protein component of high-density lipoprotein (HDL), thus inducing the formation of apoAI-apoAII heterodimers. It can also cause nitration and chlorination of tyrosine residues. Determining the apoAI-apoAII heterodimer could provide useful information as to functional changes in HDL and/or the progression of atherosclerotic lesions. To this end, the apoAI-apoAII heterodimer was identified in normal human serum by immunoblotting; the band intensity was increased by treatment with myeloperoxidase. This apparent increase in heterodimer formation was quantitatively confirmed by ELISA. In normal human serum, a significant correlation between the concentrations of apoAI-apoAII heterodimer and free apoAII (r=0.763), but not free apoAI (r=0.093), was observed, indicating that heterodimer formation is likely induced on HDL particles carrying both apoAI and apoAII (Lp-AI/AII). In preliminary studies, the levels of apoAI-apoAII heterodimer were statistically higher in plasma from subjects with acute myocardial infarction (AMI) as compared to controls. These findings indicate the possibility that the apoAI-apoAII heterodimer, including nitration and chlorination modifications, may serve as an indicator of atherosclerotic lesions.

Citation

Takahiro Kameda, Yoko Usami, Saki Shimada, Go Haraguchi, Kazuyuki Matsuda, Mitsutoshi Sugano, Yuriko Kurihara, Mitsuaki Isobe, Minoru Tozuka. Determination of myeloperoxidase-induced apoAI-apoAII heterodimers in high-density lipoprotein. Annals of clinical and laboratory science. 2012;42(4):384-91

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PMID: 23090734

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