Leukocyte migration in adipose tissue of mice null for ICAM-1 and Mac-1 adhesion receptors.
OBJECTIVE
To determine whether the leukocyte adhesion receptors ICAM-1 and Mac-1, regulators of immune cell migration, have an intrinsic role within adipose tissue by 1) analyzing the expression of ICAM-1 in adipose tissue, 2) identifying leukocyte populations within adipose tissue, and 3) determining whether ICAM-1 and Mac-1 mutant mice exhibit abnormal numbers of adipose tissue leukocytes.


METHODS
Wild-type, ICAM-1(-/-), and Mac-1(-/-) mice were fed a long-term high-fat diet. ICAM-1 expression was analyzed by Northern blot and immunohistochemistry. Leukocytes within adipose tissue were identified by immunohistochemistry and flow cytometry.


RESULTS
ICAM-1 was expressed in adipose tissue and localized to the vascular endothelium. Macrophages and lymphocytes were prevalent within the stromal-vascular cell fraction of adipose tissue, and gender-specific differences were observed, with adipose tissue from female mice containing significantly more macrophages than tissue from male mice. Numbers of leukocytes in ICAM-1(-/-) and Mac-1(-/-) mice were not different from wild-types, however, indicating that these adhesion receptors are not required for leukocyte migration into adipose tissue.


CONCLUSIONS
Our results documented leukocyte populations within adipose tissue, which may be involved in the development of heightened inflammation that is characteristic of obesity.
Robker
Rebecca L
RL
Section of Leukocyte Biology, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Avenue, Houston, TX 77030, USA.
Collins
Robert G
RG
Beaudet
Arthur L
AL
Mersmann
Harry J
HJ
Smith
C Wayne
CW
D000273:Adipose Tissue / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D002465:Cell Movement / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012313:RNA / Q000737:chemistry / Q000235:genetics
D016177:Macrophage-1 Antigen; D018799:Intercellular Adhesion Molecule-1; D012313:RNA