Insulin and glucose play a role in foam cell formation and function.
BACKGROUND
Foam cell formation in diabetic patients often occurs in the presence of high insulin and glucose levels. To test whether hyperinsulinemic hyperglycemic conditions affect foam cell differentiation, we examined gene expression, cytokine production, and Akt phosphorylation in human monocyte-derived macrophages incubated with two types of oxidized low density lipoprotein (LDL), minimally modified LDL (mmLDL) and extensively oxidized LDL (OxLDL).


RESULTS
Using Affymetrix GeneChip arrays, we found that several genes directly related to insulin signaling were changed. The insulin receptor and glucose-6-phosphate dehydrogenase were upregulated by mmLDL and OxLDL, whereas insulin-induced gene 1 was significantly down-regulated. In hyperinsulinemic hyperglycemic conditions, modified LDL upregulated Akt phosphorylation and expression of the insulin-regulated aminopeptidase. The level of proinflammatory cytokines, IL-lbeta, IL-12, and IL-6, and of a 5-lipoxygenase eicosanoid, 5-hydroxyeicosatetraenoic acid (5-HETE), was also increased.


CONCLUSIONS
These results suggest that the exposure of macrophages to modified low density lipoproteins in hyperglycemic hyperinsulinemic conditions affects insulin signaling and promotes the release of proinflammatory stimuli, such as cytokines and eicosanoids. These in turn may contribute to the development of insulin resistance.
Shashkin
Pavel N
PN
Cardiovascular Research Center, University of Virginia, 415 Lane Road, Charlottesville, VA 22903, USA. pshashkin@hotmail.com
Jain
Nitin
N
Miller
Yury I
YI
Rissing
Benjamin A
BA
Huo
Yuqing
Y
Keller
Susanna R
SR
Vandenhoff
George E
GE
Nadler
Jerry L
JL
McIntyre
Thomas M
TM
D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D005487:Foam Cells / Q000166:cytology* / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis; D007328:Insulin / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000145:classification / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
D016207:Cytokines; D006893:Hydroxyeicosatetraenoic Acids; D007328:Insulin; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D002784:Cholesterol; D051057:Proto-Oncogene Proteins c-akt; D005947:Glucose