May-Zhang-jbc.RA117.001099.pdf
Cardiovascular disease (CVD) risk depends
on HDL function, not HDL-cholesterol
(HDL-C). Isolevuglandins (IsoLGs) are lipid dicarbonyls
that react with lysine residues of proteins
and phosphatidylethanolamine. IsoLG adducts
are elevated in atherosclerosis. The consequences
of IsoLG modification of HDL have not
been studied. We hypothesized that IsoLG modification
of apoA-I deleteriously alters HDL
function. We determined the effect of IsoLG on
HDL structure-function, and whether pentylpyridoxamine
(PPM), a dicarbonyl scavenger,
can preserve HDL function. IsoLG-adducts
in HDL derived from patients with familial hypercholesterolemia
(n=10, 233.4±158.3 ng/mg)
were found to be significantly higher than in
healthy controls (n=7, 90.1±33.4 pg/mg protein).
Further, HDL exposed to myeloperoxidase had
elevated IsoLG-lysine adducts (5.7 ng/mg protein)
compared to unexposed HDL (0.5 ng/mg
protein). Preincubation with PPM reduced
IsoLG-lysine adducts by 67%, while its inactive
analogue pentylpyridoxine (PPO) did not. Addition
of IsoLG produced apoA-I and apoA-II
crosslinks beginning at 0.3 molar equivalents
IsoLG per mol apoA-I (0.3 eq.), while succinylaldehyde
and 4-hydroxynonenal (HNE) required
10 and 30 eq. IsoLG increased HDL size, generating a subpopulation of 16-23 nm. 1 eq.
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times} span.s1 {font: 7.0px Times} span.s2 {font: 11.0px Helvetica}IsoLG decreased HDL-mediated 3H-cholesterol
efflux from macrophages via ABCA1, which
corresponded to a decrease in HDL-apoA-I exchange
from 47.4% to only 24.8%. This suggests
that IsoLG inhibits apoA-I from disassociating
from HDL to interact with ABCA1. Addition of
0.3 eq IsoLG ablated HDL’s ability to inhibit
LPS-stimulated cytokine expression by macrophages,
and increased IL-1β expression by 3.5-
fold. The structural-functional effects were partially
rescued with PPM scavenging.
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times} span.s1 {font: 7.0px Times} span.s2 {font: 11.0px Helvetica}generating a subpopulation of 16-23 nm. 1 eq.
IsoLG decreased HDL-mediated 3H-cholesterol
efflux from macrophages via ABCA1, which
corresponded to a decrease in HDL-apoA-I exchange
from 47.4% to only 24.8%. This suggests
that IsoLG inhibits apoA-I from disassociating
from HDL to interact with ABCA1. Addition of
0.3 eq IsoLG ablated HDL’s ability to inhibit
LPS-stimulated cytokine expression by macrophages,
and increased IL-1β expression by 3.5-
fold. The structural-functional effects were partially
rescued with PPM scavenging.
