Serum amyloid A and lipoprotein retention in murine models of atherosclerosis.
OBJECTIVE
Elevated serum amyloid A (SAA) levels are associated with increased cardiovascular risk in humans. Because SAA associates primarily with lipoproteins in plasma and has proteoglycan binding domains, we postulated that SAA might mediate lipoprotein retention on atherosclerotic extracellular matrix.


RESULTS
Immunohistochemistry was performed for SAA, apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), and perlecan on proximal aortic lesions from chow-fed low-density lipoprotein receptor (LDLR)-/- and apoE-/- mice euthanized at 10, 50, and 70 weeks. SAA was detected on atherosclerotic lesion extracellular matrix at all time points in both strains. SAA area correlated highly with lesion areas (apoE-/-, r=0.76; LDLR-/-, r=0.86), apoA-I areas (apoE-/-, r=0.88; LDLR-/-, r=0.80), apoB areas (apoE-/-, r=0.74; LDLR-/-, r=0.89), and perlecan areas (apoE-/-, r=0.83; LDLR-/-, r=0.79) (all P<0.0001). In vitro, SAA enrichment increased high-density lipoprotein (HDL) binding to heparan sulfate proteoglycans, and immunoprecipitation experiments using plasma from apoE-/- and LDLR-/- mice demonstrated that SAA was present on both apoA-I-containing and apoB-containing lipoproteins.


CONCLUSIONS
In chow-fed apoE-/- and LDLR-/- mice, SAA is deposited in murine atherosclerosis at all stages of lesion development, and SAA immunoreactive area correlates highly with lesion area, apoA-I area, apoB area, and perlecan area. These findings are consistent with a possible role for SAA-mediated lipoprotein retention in atherosclerosis.
O'Brien
Kevin D
KD
Division of Cardiology, University of Washington, Seattle, WA 98195-6422, USA. cardiac@u.washington.edu
McDonald
Thomas O
TO
Kunjathoor
Vidya
V
Eng
KimLi
K
Knopp
Eleanor A
EA
Lewis
Katherine
K
Lopez
Roland
R
Kirk
Elizabeth A
EA
Chait
Alan
A
Wight
Thomas N
TN
deBeer
Frederick C
FC
LeBoeuf
Renee C
RC
D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism*; D001055:Apolipoproteins B / Q000378:metabolism*; D001057:Apolipoproteins E / Q000235:genetics; D001161:Arteriosclerosis / Q000378:metabolism* / Q000473:pathology; D002784:Cholesterol / Q000097:blood; D004195:Disease Models, Animal; D005260:Female; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D007150:Immunohistochemistry; D008075:Lipoproteins, HDL / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D011973:Receptors, LDL / Q000235:genetics; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D012850:Sinus of Valsalva / Q000473:pathology
D016632:Apolipoprotein A-I; D001055:Apolipoproteins B; D001057:Apolipoproteins E; D019812:Heparan Sulfate Proteoglycans; D008075:Lipoproteins, HDL; D011973:Receptors, LDL; D000685:Serum Amyloid A Protein; C071927:perlecan; D002784:Cholesterol