Key result
APOA4 on small HDL was catabolized approximately three times faster (2.1-2.5 pools/d) than APOA4 on large HDL (0.78-0.84 pools/d) and appeared in circulation earlier, indicating distinct origins for small and large APOA4-HDL particles.
Why the study?
APOA4's functions on HDL in humans are not well understood, prompting investigation into its origin and function by studying metabolism across 6 HDL sizes.
Observational (n=12)
No
The distinct metabolic profiles of APOA4 on small versus large HDL suggest that APOA4 on small HDL originates directly from the small intestine, while APOA4 on large HDL originates from chylomicron transfer.
Distinct APOA4 kinetics on small versus large HDL suggest differential origins; leaves open intestinal HDL subspecies as targets for future cardiometabolic studies.
Apolipoprotein A4's (APOA4's) functions on HDL in humans are not well understood. A unique feature of APOA4 is that it is an intestinal apolipoprotein secreted on HDL and chylomicrons. The goal of this study was to gain a better understanding of the origin and function of APOA4 on HDL by studying its metabolism across 6 HDL sizes. Twelve participants completed a metabolic tracer study. HDL was isolated by APOA1 immunopurification and separated by size. Tracer enrichments for APOA4 and APOA1 were determined by targeted mass spectrometry, and metabolic rates were derived by compartmental modeling. APOA4 metabolism on small HDL (alpha3, prebeta, and very small prebeta) was distinct from that of APOA4 on large HDL (alpha0, 1, 2). APOA4 on small HDL appeared in circulation by 30 minutes and was relatively rapidly catabolized. In contrast, APOA4 on large HDL appeared in circulation later (1-2 hours) and had a much slower catabolism. The unique metabolic profiles of APOA4 on small and large HDL likely indicate that each has a distinct origin and function in humans. This evidence supports the notion that APOA4 on small HDL originates directly from the small intestine while APOA4 on large HDL originates from chylomicron transfer.
No takes yet. Share an insight, caveat, or question.
Andraski et al. (2023) conducted an observational in Low HDL-cholesterol and overweight or obesity (n=12). APOA4 on small HDL (alpha3, prebeta, prebeta-b) vs. APOA4 on large HDL (alpha0, 1, 2) was evaluated on Fractional catabolic rate (FCR) of APOA4. APOA4 on small HDL was catabolized approximately three times faster (2.1-2.5 pools/d) than APOA4 on large HDL (0.78-0.84 pools/d) and appeared in circulation earlier, indicating distinct origins for small and large APOA4-HDL particles.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: