Proteomic analysis and comparison of intra- and extracranial cerebral atherosclerosis responses to hyperlipidemia in rabbits

The present study aimed to investigate protein expression levels of intra- and extracranial atherosclerosis in rabbits following administration of a high-fat diet. Rabbits were randomly divided into control (group A; n=9) and high-fat diet (group B; n=9) groups. At week 12, tissues were sectioned from the common carotid artery (CCA) and middle cerebral artery (MCA). Pathological analysis was performed. Differential protein expression levels were examined by 2-D gel electrophoresis (2-DE) and mass spectrometry (MS) analysis and validated by western blotting. Serum lipid levels, the intima-media thickness (IMT) and degree of atherosclerosis of the CCA and MCA were increased at week 12 in the high-fat diet group compared with rabbits that received a normal diet. 2-DE and MS analysis of the protein extracted from CCA and MCA detected >439 different proteins; the expression of 25 proteins was altered, and 8 proteins [albumin A chain, tropomyosin α-1 chain (TPM1), heat shock protein 70 (HSP70), α-smooth muscle actin, β-galactose binding agglutinin, TPM4 isoform 2, cell keratin 9, single octylic acid glyceride β-2) demonstrated significant alterations in expression levels. Due to limited antibody sources, only three differentially expressed proteins (TPM1, HSP70 and α-smooth muscle actin) were examined by western blotting. The results of our previous study demonstrated that hyperlipidemia affected the IMT of intracranial and extracranial cerebral arteries. In the present study, protein expression levels of TPM1 and α-smooth muscle actin from extracranial cerebral arteries were significantly increased compared with intracranial cerebral arteries; however, protein expression levels of HSP70 from intracranial cerebral arteries was increased compared with extracranial cerebral arteries. The differences may be closely associated with cell proliferation and metastasis, and oxidoreduction, in intra- and extracranial cerebral atherosclerosis. HSP70 may have protective properties against atherosclerosis via underlying anti-inflammatory mechanisms, furthermore, differential protein expression levels (TPM1, HSP70 and α-smooth muscle actin) between intra- and extracranial cerebral arteries may facilitate the identification of novel biological markers for the diagnosis and treatment of cerebral arteriosclerosis.