Diabetes, Vol 49, Issue 6 1064-1069, Copyright © 2000 by American Diabetes Association
Effect of hyperglycemia and hyperlipidemia on atherosclerosis in LDL receptor-deficient mice: establishment of a combined model and association with heat shock protein 65 immunity
P Keren, J George, A Shaish, H Levkovitz, Z Janakovic, A Afek, I Goldberg, J Kopolovic, G Keren and D Harats
Institute of Lipid and Atherosclerosis Research, Sheba Medical Center, Tel-Hashomer, Israel.
Diabetes and atherosclerosis have been proposed to be influenced by immune
and autoimmune mechanisms. A common incriminated antigen in both disorders
is the heat shock protein (HSP)-60/65. In the current study, we established
a model combining hyperglycemia with hyperlipidemia in LDL
receptor-deficient (LDL-RD) mice and assessed its possible influences on
lipid profile, HSP60/65, and atherogenesis. LDL-RD mice were injected
either with streptozotocin to induce hyperglycemia or with citrate buffer
(control). When hyperglycemia was induced, both study groups were
challenged with a high-fat (Western) diet for 6 weeks. Plasma fasting
glucose, lipid profile, and antibody levels to HSP65 and oxidized LDL were
assessed. At death, the spleens from both groups were evaluated for their
proliferative response to HSP65 and the consequent cytokine production. The
extent of atherosclerosis was assessed at the aortic sinus. Plasma glucose,
cholesterol, and triglyceride levels were elevated in mice injected with
streptozotocin compared with control mice. Atherosclerotic lesions were
significantly larger in the streptozotocin-injected hyperglycemic LDL-RD
mice (132 +/- 23 x 10(5) microm2) in comparison to their normoglycemic
litter-mates (20 +/- 6.6 x 10(5) microm2; P < 0.0001). Both humoral and
cellular immune response to HSP65 was more pronounced in
streptozotocin-injected mice. When challenged with HSP65 in vitro,
splenocytes from streptozotocin-injected mice favored the production of the
T-helper (TH)-1 cytokine gamma-interferon. In conclusion, we have
established a mouse model that combines hyperglycemia with diet-induced
hyperlipidemia in LDL-RD mice and studied its effect on atherosclerosis
progression. The accelerated atherosclerotic process is associated with
heightened immune response to HSP65 and a shift to a TH1 cytokine profile.