LpA-II:B:C:D:E: a new immunochemically-defined acute phase lipoprotein in humans

Area of Science:

• Biochemistry
• Immunology
• Lipid Metabolism

Background:

• Conventional ultracentrifugation of lipoproteins yields heterogeneous fractions.
• Apoproteins play crucial roles in host defense.
• Previous studies lacked information on apoprotein-defined lipoprotein subclasses.

Purpose of the Study:

• To characterize changes in immunochemically distinct lipoprotein subclasses during experimental endotoxemia.
• To investigate the role of apoprotein content in lipoprotein subclass dynamics.

Main Methods:

• Studied apoB- and apoA-containing lipoprotein subclasses in 12 healthy male volunteers.
• Administered a single dose of endotoxin (ET; 2 μg/kg) to induce inflammation.
• Monitored lipoprotein changes for 8 hours post-endotoxin administration.

Main Results:

• Endotoxin decreased TG, TC, apoB, LpB, Lp:B:C, and LpB:C:E+ LpB:E subclasses.
• A distinct triglyceride-rich lipoprotein subclass (LpA-II:B:C:D:E) increased by 49% above baseline at 8 hours.
• This increase designates LpA-II:B:C:D:E as an acute phase protein, suggesting post-translational modification and particle formation.

Conclusions:

• Identified a novel acute phase lipoprotein (LpA-II:B:C:D:E) during endotoxemia.
• This lipoprotein possesses apoprotein constituents with metabolic and immunoregulatory properties.
• The findings highlight its potential role in host defense and the acute phase response (APR).