ApoE(-/-)/lysozyme M(EGFP/EGFP) mice as a versatile model to study monocyte and neutrophil trafficking in atherosclerosis.
OBJECTIVE
Intravital microscopy is a useful tool for studying leukocyte trafficking in atherosclerosis. However, distinction between various subclasses of leukocytes using this technology is lacking. Therefore, we generated ApoE(-/-)/Lysozyme M(EGFP/EGFP) mice and investigated whether targeted cell types could be visualized by in vivo microscopy and whether absence of lysozyme M will influence atherosclerosis.


METHODS
We crossed male ApoE(-/-) mice with mice homozygous for a knock-in mutation of enhanced green fluorescent protein (EGFP) in the lysozyme M locus (Lys(EGFP/EGFP)) creating ApoE(-/-)/Lys(EGFP/EGFP) mice. Mice were sacrificed at the age of 26 weeks. Blood was collected for serum lipid analysis, differential white blood cell count and flow cytometry. Lesion area was determined on en face mounted aortas and sections from aortic roots were stained for immunohistochemistry. Atherosclerotic lesions were also studied by confocal- and intravital microscopy.


RESULTS
Basic parameters, such as white blood cell count, cholesterol profile, lesion area and plaque composition was unaltered in ApoE(-/-)/Lys(EGFP/EGFP) mice compared to ApoE(-/-) mice. Fluorescent neutrophils and monocytes were clearly visualized by intravital fluorescence and confocal microscopy. Fluorescent cells were distributed primarily in the periphery of atherosclerotic lesions indicating a preference for recruitment in these areas.


CONCLUSIONS
ApoE(-/-)/Lys(EGFP/EGFP) mice will serve as a useful model to study leukocyte trafficking in atherosclerosis and how different subsets of leukocytes influence atherogenesis.
Department of Physiology and Pharmacology, Karolinska Institute, S-171-77 Stockholm, Sweden. Pierre.Rotzius@ki.se
Pierre
P
Rotzius
Oliver
O
Soehnlein
Ellinor
E
Kenne
Lennart
L
Lindbom
Kristofer
K
Nystrom
Sebastian
S
Thams
Einar E
EE
Eriksson
D000818:Animals; D001011:Aorta / Q000378:metabolism; D001057:Apolipoproteins E / Q000235:genetics* / Q000378:metabolism; D050197:Atherosclerosis / Q000378:metabolism*; D004195:Disease Models, Animal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006720:Homozygote; D007962:Leukocytes / Q000166:cytology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000378:metabolism*; D009113:Muramidase / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D017382:Reactive Oxygen Species
D001057:Apolipoproteins E; D017382:Reactive Oxygen Species; D049452:Green Fluorescent Proteins; D009113:Muramidase